Game Roadmap

The game is not an attempt to reproduce the arbitrary recipes, crafting grids, or tier ladders of a traditional block game. Voxamine replaces those conventions with real thermodynamics, electrochemistry, and industrial hazard management.

The foundational design commitment is defined in Masterplan §27.7: to teach that matter matters. Progression is not governed by unlocked recipes; it is governed by capability—the temperature, pressure, containment, and chemical conditions the player can achieve, control, and survive. Every simplification in the simulation must be a simplification in the direction of truth, never a falsehood.

[!IMPORTANT] The No-Unlearning Principle (§27.7): A model may omit detail to remain computable, but it may never invent a phenomenon or contradict established physics merely for game balance. Everything the player learns by operating the game must remain true in the real world.

This roadmap outlines the complete engineering journey defined in Masterplan §36: from the pure headless thermodynamic solver to the Chemistry MVP (C0–C7), followed by the post-MVP expansion horizons (C8–C17) culminating in steady-state stellarator fusion and closed-loop interstellar life support.

---

Live Engineering Status Dashboard

The table below reflects the live build and gate status as verified across the codebase and recorded in Docs/HANDOFF.md.

Milestone	Title	Tier	Core Capability Unlocked	Live Status	Evidence / Gate Artifact
C0	Thermodynamic Core	T0–T2	Shomate $C_p(T)$, $\Delta G^\circ$, detailed balance kinetics, Nernst $\Delta G = -nFE$, zero managed GC.	Complete & Landed	Headless validation suite; 10,000 randomized scenario conservation tests.
C1	Vessels & Apparatus	T1–T3	Enclosed reaction domains, wall stress envelopes, $T^4$ radiative and convective heat transfer.	Complete & Landed	Pyrolysis, calcination, and reduction testbeds; apparatus thermal failure proofs.
C1-P	Player Interaction Slice	T1–T4	Complete in-world loop: placement, targeting, batch charging, Planckian glow, after-action card, save/reload.	Closed & Verified	Docs/Gates/c1p/ (c1p-reduction.png, c1p-failed.png, c1p-reload.png).
C2	Geology, Grade & Assay	T0–T5	Continuous deposit grade fields (OreGradeMath), bulk matter charging, honest error bars ($|m - t| \le \sigma$).	Active / Advanced	Docs/Gates/c2-assay/ (c2-assay.png, 12/12 checks passed). C2.5 slag & C2.6 beneficiation in progress.
C3	Atmospheric Hazards	T1–T5	Sparse domains ($\le 64$), 6-connected room scanner, multizone transport, nonlinear CFK $COHb$ vitals, Stone Vents.	Active / Advanced	Docs/Gates/c3-warning/ (8/8), Docs/Gates/c3-ventilation/ (10/10), Docs/Gates/c3-rupture/ (11/11).
C4	Industrial Logistics & Power	T4–T5	Crushers, screens, jigs, gravity chutes, powered conveyor belts ($\le 4096$ items), shafts, flyball governors.	Up Next	30-minute continuous hands-off copper production line gate.
C5	Knowledge, Notebook & Leads	T0–T5	Persistent LabNotebook model, optical observation quality tiers, event-derived hypotheses, verified achievements.	Planned	Unassisted first-time player playtest reaching copper via journal affordances alone.
C6	Content, Balance & Pacing	T0–T5	Full T0–T5 chemical catalogue, hours 0–20 survival arc, copper moment summit, reaction audio/VFX, onboarding.	Planned	Formative playtest suite passing the §36.9 decision, comprehension, and recovery protocol.
C7	Chemistry MVP Release Candidate	T0–T5	24-hour soak tests, memory and frame budget compliance, save compaction, clean standalone build.	Planned	Final sign-off against the 8 outcomes of the Chemistry MVP Definition of Done (§36.6).
C8–C10	Glass, Solutions & Acids	T6–T10	Soda-lime glassware, Debye–Hückel aqueous equilibria, hydrometallurgical leaching, chamber mineral acids.	Horizon	Post-MVP milestone sequence.
C11–C13	Electrochemistry & Metals	T11–T13	Galvanic cells, batteries, chlor-alkali, Hall–Héroult molten salt electrolysis, dynamos, light reactive metals.	Horizon	The master technological capability unlock (§28.6).
C14–C15	Closed Loops & Advanced Materials	T14–T16	Hydroponics, flue-gas $CO_2$ scrubbers, converter steel, cryogenics, superconducting magnet coils.	Horizon	Precision industrial ecosystem.
C16	Stellarator Fusion Plasma	T17–T19	3D modular coil geometry, magnetic diagnostics, real-time MHD feedback, sustained $Q_{\text{plasma}} > 1$.	Horizon	The scientific summit of the terrestrial game (§35.2).
C17	The Voyage	T20	Interstellar exploration vessel, aneutronic fusion propulsion, zero-margin closed-cycle life support.	Horizon	The ultimate technological culmination (§35.3).

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The P-Gate Contract (§36.4a)

During early development, milestones C0 through C2 produced correct, mass-conserving, rigorously tested chemistry that ran entirely headlessly. However, because no player-facing interface had been wired to those systems, players had no way to experience or manipulate them in-game.

To prevent simulation code from drifting away from the player experience, §36.4a establishes the Player-Interaction Gate (P-Gate). Every milestone from C1 onward must close a P-gate in a clean build of the Gameplay.unity scene before subsequent milestone work can open.

flowchart LR
    subgraph Headless["Headless Engineering"]
        direction TB
        M[Mathematical Model] --> T[EditMode Tests]
        T --> W[Voxel Workshop Tooling]
    end

    subgraph PGate["The P-Gate Contract (§36.4a)"]
        direction TB
        R[1. Reachable\nNormal input & verbs]
        L[2. Legible\nTruthful in-world clues]
        D[3. Durable\nExact save & bit-identical reload]
    end

    subgraph Landed["Landed Gameplay Feature"]
        C[Audited Gate Artifact\nDocs/Gates/gate-id/]
    end

    Headless -->|Necessary but insufficient| PGate
    PGate -->|Verified in clean build| Landed

    classDef headless fill:#182230,stroke:#3b82f6,color:#93c5fd;
    classDef pgate fill:#1c1917,stroke:#f59e0b,color:#fde68a;
    classDef landed fill:#064e3b,stroke:#10b981,color:#a7f3d0;

    class M,T,W headless;
    class R,L,D pgate;
    class C landed;

The Three Mandatory Conditions

A P-gate closes only when all three conditions hold simultaneously in a clean build of the Gameplay scene:

1. Reachable: The player operates the slice with normal input—movement, view rotation, the interact verb, and the inventory. No Unity Editor, no Play-mode inspector overrides, no console commands, and no Voxel Workshop diagnostic windows anywhere in the loop.
2. Legible: The player discovers what happened through in-world physical phenomena or the laboratory notebook. A simulation truth that appears only in a unit test assertion, console log, or inspector window has not been presented to the player. Crucially, invisible hazards remain invisible: carbon monoxide receives no artificial tint, aroma, or supernatural HUD icon; players must deduce hazards from physical flame behaviour, soot, and real physiological symptoms.
3. Durable: The slice survives an atomic save → quit → reload cycle. The causal event stream remains intact, mass and charge are conserved to the mole, and continued simulation resumes bit-identically from the exact point of interruption without unearned offline fast-forwarding (§29.5).

What Explicitly Does Not Close a P-Gate

The following tools are valuable for development and testing, but they do not satisfy a P-gate:

[!WARNING]

• EditMode or PlayMode tests: Tests prove that the underlying mathematical model works; they do not prove that a player can reach or operate it.
• Voxel Workshop modules: The Voxel Workshop is permanently an authoring and diagnostic surface for developers (§18). It is never the player’s interface, and a module is never evidence that one exists.
• Console logs and debug overlays: Information buried in logs is invisible to standard gameplay.
• Uninstantiated runtime components: A MonoBehaviour that would work if an object instantiated it does not count; omitting the instantiation is considered an active defect.

Gate Evidence Artifacts

Every closed P-gate commits an immutable artifact bundle under Docs/Gates/<gate-id>/:

• The -batchmode Editor test harness driving the slice (under Assets/_Game/Editor/Gates/).
• <gate-id>.png: A high-resolution capture of the player-visible result in the clean gameplay scene.
• <gate-id>.txt: The harness’s deterministic assertion output, including conservation residuals.

A gate asserted in text without a committed artifact bundle is considered open.

---

The 5-Field Task Architecture (§36.4)

From milestone C1-P onward, all engineering tasks are authored using a strict five-field format. This format ensures that a single task maps to a single agent session’s work with clear, self-contained boundaries:

- Depends    — Hard prerequisite task IDs that must be closed first.
- Touches    — Exact file paths or directories expected to change.
- Do         — The physical change, expressed in outcome terms.
- Done when  — A single falsifiable assertion verifiable by test or gate harness.
- Out of scope — Adjacent work this task must NOT absorb (binding scope defense).

[!TIP] Defending Against Scope Creep: The Out of scope field is binding on all implementation. If an agent discovers that a task requires editing outside its declared Touches surface, it must stop and re-split the task rather than silently expanding the boundary.

---

Milestone Dependency Graph

The roadmap is strictly ordered by physical and technological dependencies. A downstream milestone never begins while an upstream correctness gate remains open.

flowchart TD
    C0["C0: Thermodynamic Core\n(Complete)"] --> C1["C1: Vessels & Apparatus\n(Complete)"]
    C1 --> C1P["C1-P: Player Vertical Slice\n(Closed & Verified)"]
    
    C1P --> C2["C2: Geology & Ore Assay\n(Active / Advanced)"]
    C1P --> C3["C3: Hazards & Ventilation\n(Active / Advanced)"]
    
    C2 --> C4["C4: Industrial Logistics & Power\n(Up Next)"]
    C3 --> C4
    
    C4 --> C5["C5: Knowledge & Notebook\n(Planned)"]
    C5 --> C6["C6: Content, Balance & Onboarding\n(Planned)"]
    C6 --> C7["C7: Chemistry MVP Release Candidate\n(Planned)"]

    subgraph PostMVP["Post-MVP Horizons (Masterplan §36.8 & §35)"]
        direction TB
        C8["C8: Glassware"] --> C9["C9: Aqueous Solutions"]
        C9 --> C10["C10: Mineral Acids"]
        C10 --> C11["C11: Electrochemistry & Electrolysis"]
        C11 --> C12["C12: Electromagnetics & Dynamos"]
        C11 --> C13["C13: Reactive Metals"]
        C12 --> C14["C14: Hydroponics & Closed Loops"]
        C13 --> C15["C15: Advanced Materials & Cryogenics"]
        C14 --> C16["C16: Stellarator Fusion Plasma"]
        C15 --> C16
        C16 --> C17["C17: The Voyage"]
    end

    C7 -.-> PostMVP

    classDef done fill:#064e3b,stroke:#10b981,color:#a7f3d0;
    classDef active fill:#1e3a5f,stroke:#3b82f6,color:#bfdbfe;
    classDef planned fill:#1c1917,stroke:#78716c,color:#e7e5e4;
    classDef future fill:#311042,stroke:#a855f7,color:#f3e8ff;

    class C0,C1,C1P done;
    class C2,C3 active;
    class C4,C5,C6,C7 planned;
    class C8,C9,C10,C11,C12,C13,C14,C15,C16,C17 future;

---

Chemistry MVP Milestones (C0–C7)

C0 — Thermodynamic Core

Status: Complete & Landed

The mathematical and physical foundation of the simulation. Implemented headlessly with zero Unity dependencies to guarantee strict determinism and numerical rigor.

• Scope:
  • NIST-JANAF 7-coefficient Shomate polynomials for heat capacity $C_p(T)$, standard enthalpy $\Delta H^\circ(T)$, entropy $\Delta S^\circ(T)$, and Gibbs free energy $\Delta G^\circ(T)$.
  • Temperature-dependent equilibrium constants $K(T) = \exp(-\Delta G^\circ / RT)$.
  • Reversible reaction kinetics satisfying detailed balance: $r_f / r_r = K$.
  • Electrochemical half-reactions, standard reduction potentials $E^\circ$, the thermodynamic bridge $\Delta G^\circ = -nFE^\circ$, and the Nernst equation for non-standard conditions.
  • Multi-phase energy balances, latent heats of fusion and vaporisation, and deterministic sub-stepping.
• Pass Criteria:
  • Validated against empirical physical data within tight tolerances: $\text{CaCO}_3$ decomposition equilibrium pressure, Boudouard reaction ($C + CO_2 \rightleftharpoons 2CO$), and adiabatic carbon/oxygen flame temperatures.
  • Exact atomic and charge conservation across 10,000 randomised reaction scenarios.
  • Bit-identical cross-platform determinism across target operating systems and runtimes.
  • Zero steady-state managed memory allocations in the chemistry solver.

C1 — Vessels & Apparatus

Status: Complete & Landed

Physical apparatus enclosing thermodynamic reaction domains and handling heat exchange with the world.

• Scope:
  • Vessel forms: crude pit, ceramic crucible, clamp kiln, retort, and refractory furnace.
  • Wall materials with explicit structural, thermal, and chemical stress envelopes (thermal shock, maximum pressure ratings, wall erosion).
  • Configurable port topology, flow restrictions, passive venting, and pressure relief valves.
  • Heat transfer models: conduction through walls, convective boundary layers, radiative loss ($T^4$), and environmental cooling.
  • Dormancy and quiescence logic to put static vessels to sleep without loss of fidelity.
• Pass Criteria:
  • A player can pyrolyse wood to charcoal, calcine limestone to quicklime, and reduce malachite to molten copper.
  • Inadequate vessels fail under thermal shock or overpressure, while refractory designs endure.
  • Causal logging via compact ScienceEvent records.

C1-P — The Player Reaches the Chemistry

Status: Closed & Verified (c1p Gate Passed)

The hard-blocking integration slice connecting player interaction to the headless chemistry core. Prior to C1-P, extensive chemistry code existed but remained completely unreachable in-game.

• The Six Integration Tasks:
  1. C1-P.1 (Physical Vessel): Procedurally instantiated vessel form in Gameplay.unity with physical collision and placement validation.
  2. C1-P.2 (Targeting): Center-screen raycasting extended through BlockInteractionController to outline and select in-world vessels.
  3. C1-P.3 (Charging): Carried bulk ore batches charged into targeted vessels via the interact verb with strict all-or-nothing mass conservation.
  4. C1-P.4 (Planckian Glow): Vessel fires at 20 Hz; real-time surface temperature drives physically grounded Planckian blackbody emission shaders as an in-world thermometer.
  5. C1-P.5 (After-Action Card): Minimal HUD card rendering causal AfterActionLine[] narratives, respecting epistemic bounds (unobserved reactions and hidden quantities remain unstated).
  6. C1-P.6 (Durable Save/Reload): Exact round-trip serialization of vessel state, charge moles, and event stream via AtomicWorldSaveFile.
• Committed Evidence: Docs/Gates/c1p/ contains the committed gate harness output, verification logs, and screenshots demonstrating mining, charging, thermal glowing, causal narrative inspection, and save/reload persistence.

C2 — Block Composition, Geology, and Ore Assay

Status: Active / Advanced

Grounding world generation and mining in variable geochemistry rather than homogenous block drops.

• Sub-Tasks:
  • C2.1 (Block Composition) · Landed: BlockDefinition.Composition and BlockCompositionCharging bridges.
  • C2.2 (Ore-Body Grade Fields) · Landed: Continuous procedural grade fields (OreGradeMath) with rich cores, lean halos, and skewed deposit geometries. Grade is computed on demand via TerrainGenerator.GetOreGradeAt.
  • C2.3 (Batch Charging) · Landed: Mined blocks convert into MaterialBatch instances carrying mass and composition, charged into vessels via MaterialBatchCharging.
  • C2.4 (Assay Mathematics) · Landed: Hand specimen, density measurement, and fire assay tiers enforcing the swept invariant: $$\left|\text{measured} - \text{true}\right| \le \text{uncertainty}$$
  • C2.5 (Slag Phase) · Active: Silicate gangue reacts with flux ($CaO + SiO_2 \to CaSiO_3$), producing a distinct condensed slag phase rather than disappearing.
  • C2.6 (Beneficiation) · Active: Crushing and gravity screening that increase concentration at the cost of mechanical energy and tailings losses.
  • C2.7 (Assay in Player’s Hands) · Closed P-Gate: Inventory shows unassayed ore as mass-only. Pressing F runs a hand-specimen assay with honest uncertainty bounds.
  • C2.8 (Seed Sufficiency) · Landed: Procedural verification that generated seeds guarantee minimum extractable element reserves for progression.
• Evidence: Docs/Gates/c2-assay/ commits the c2-assay P-gate artifact proving mass-only batch legibility before inspection and uncertainty-bounded assay readings.

[!NOTE] Active C2.5 Blocker: The slag-forming reaction ($CaO + SiO_2 \to CaSiO_3$) requires temperature-dependent heat capacity $C_p(T)$ data for wollastonite ($\text{CaSiO}_3$). NIST WebBook lacks a Shomate fit, and historical geochemical literature remains paywalled. Per the “No-Unlearning” principle, fitting arbitrary polynomial coefficients is prohibited; the slice is held until verified thermodynamic data is sourced.

C3 — Atmospheric Hazards & Ventilation

Status: Active / Advanced

Extending matter conservation to the surrounding environment: gases vented from vessels cannot vanish into an infinite sink.

• Sub-Tasks:
  • C3.1 (Atmospheric Domain Registry) · Landed: Up to 64 active regional gas domains managed by AtmosphericDomainRegistry. Inactive air masses sleep into a persistent regional ledger; matter is never deleted.
  • C3.2 (Vessel Venting Integration) · Landed: Open vents, relief valves, and ruptures transfer whole-mixture gas moles directly into receiving atmospheric domains.
  • C3.3 (Enclosure Scanning & Transport) · Landed: Bounded 6-connected voxel flood fill (AtmosphericEnclosureScanner) identifying airtight rooms, internal volumes, and structural openings. NIST multizone transport (AtmosphericTransportMath) models density-driven buoyancy and stack effects.
  • C3.4 (Human Physiology Core) · Landed: Nonlinear Coburn–Forster–Kane (CFK) differential integrator tracking blood carboxyhemoglobin ($COHb$) and effective blood oxygenation from ambient $CO$ partial pressure for a 70 kg reference adult.
  • C3.5 (Actionable Pre-Lethal Warnings) · Closed P-Gate: Sourced physiological cues (exertional dyspnea, headache) and environmental signals (flame colour and flickering) prompt the player to ventilate before reaching lethal thresholds.
  • C3.6 (Ventilation & Rupture) · In Progress: Player-built porous Stone Vent blocks providing effective outdoor air exchange ($Q = 0.025\text{ m}^3/\text{s}$) when an exterior path is verified.
• Evidence:
  • Docs/Gates/c3-warning/: Committed 8-check P-gate proving pre-lethal warning prompts without supernatural gas-sensing cues.
  • Docs/Gates/c3-ventilation/: Committed 10-check gate validating exterior air path detection and room flushing.
  • Docs/Gates/c3-rupture/: Committed 11-check gate confirming sealed vessel overpressure releases contents into room domains before structural failure.

C4 — Industry: Logistics, Power, and Control

Status: Up Next

Moving from manual batch processing to continuous industrial mechanics.

• Scope:
  • Continuous processing machinery: jaw crushers, vibrating screens, and mineral jigs with typed input/output ports.
  • Gravity chutes, ducts, and mechanical conveyor belts handling up to 4,096 items in flight within the frame budget.
  • Mechanical power distribution: waterwheels, drive shafts, gearboxes, and friction losses.
  • Mechanically driven bellows to sustain high-temperature blast conditions.
  • Passive mechanical control systems: centrifugal flyball governors, counterweight relief dampers, and float valves. (Electronic PID controllers, computers, and wiring remain post-MVP).
• Gate:
  • An automated processing line runs continuously for 30 minutes hands-off, converting mined ore and timber into refined copper.
  • Throughput, conversion efficiency, and energy consumption match thermodynamic predictions within stated tolerances.
  • The line recovers deterministically from simulated power cuts, blocked chutes, and material starvation.

C5 — Knowledge, Notebook, and Achievements

Status: Planned

The player’s interface to scientific discovery, causal understanding, and experimental history.

• Scope:
  • The persistent LabNotebook model, recording discovered reactions, apparatus diagrams, assay histories, and empirical notes.
  • Epistemic observation quality: observations depend on apparatus visibility (opaque clay obscures reactions; soda-lime glass allows optical verification).
  • Hypothesis leads generated dynamically from anomalous or unexpected simulation events.
  • Source-linked causal narratives explaining run outcomes, unexpected side-products, and failure modes without leaking unmeasured ground truth.
  • Flesch–Kincaid readability guardrail asserting a grade-level ceiling $\le 10$ across all generated text.
  • Simulation-verified achievements: awarded exclusively upon proof of a genuine chemical milestone in the event ledger; never triggered by arbitrary flags.
• Gate:
  • A playtester with zero external documentation discovers and produces copper using only in-game notebook clues and experimental feedback.
  • Every achievement is provably backed by a valid, conserved event stream.

C6 — Content, Balance, and Onboarding

Status: Planned

Full authoring and pacing of the initial survival arc.

• Scope:
  • The complete T0–T5 chemical catalogue with NIST/JANAF-sourced thermodynamic parameters.
  • Pacing tuning for the initial 0–20 hour survival progression, culminating in the first copper pour as an earned summit.
  • Acoustic and visual feedback for chemical phenomena: phase changes, boiling, flame coloration, gas effervescence, and mechanical strain.
  • First-hour tutorialization teaching the core loop—temperature, containment, and observation—without immersion-breaking popups.
• Gate:
  • Formative playtests demonstrate that new players can establish fire, construct an initial kiln, and diagnose early failures within target time windows.

C7 — Chemistry MVP Release Candidate

Status: Planned

Hardening, optimization, and final polish for public release.

• Scope:
  • Long-duration soak testing (continuous 24-hour simulation runs) verifying zero memory leaks and absolute mass conservation.
  • Profiled compliance with all performance budgets defined in §36.7.
  • Atomic world save format verification and save file compaction.
  • Clean multi-platform build verification.
• Gate: Full sign-off against the 8 outcomes of the Chemistry MVP Definition of Done (§36.6).

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Chemistry MVP Definition of Done (§36.6)

The Chemistry MVP is declared complete when a player, running a clean standalone build with no developer tooling, can achieve all eight falsifiable outcomes:

#	Outcome	Player Experience
1	Experimental Discovery	Start with nothing in a procedurally generated world, and discover fire, pyrolysis, calcination, and smelting through hands-on experimentation guided solely by in-world feedback.
2	Earned Copper	Prospect an authentic ore body, assay its grade, beneficiate the raw rock to discard gangue, and smelt refined copper, experiencing the pour as an earned achievement.
3	Bronze Metallurgy	Locate cassiterite deposits, reduce tin, and produce bronze as a genuine thermodynamic solution phase with enhanced mechanical properties.
4	Hazard Management	Recognize, diagnose, and prevent industrial hazards (such as $CO$ accumulation or overpressure explosions) using honest physical warnings, without artificial sensory assistance.
5	Closed-Loop Automation	Construct an automated continuous production line, calculating stoichiometric requirements from balanced chemical equations and accounting for losses and throughput bottlenecks.
6	Scientific Notebook	Review a comprehensive, self-authoring laboratory notebook that preserves experimental history, causal deductions, and evidence-verified achievements.
7	Exact State Durability	Save, exit, and reload the game at any point, finding all apparatus, material inventories, active atmospheric volumes, and notebooks completely intact and continuing bit-identically.
8	Honest Epistemology	Investigate any process or accident through the in-game journal to inspect a causal, uncertainty-bounded account of mass and energy transport, without leaking unmeasured simulation data.

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Testing Strategy & Invariant Hierarchy (§36.5)

The chemistry core carries the project’s heaviest testing burden because it is pure, headless, and fast to execute. Every pull request and release is validated against a twelve-point invariant hierarchy:

1. Empirical Validation Suite: Sourced reference values from Docs/CHEMISTRY_SOURCES.md tested against explicit tolerances. A failing validation test is treated as a physics defect and blocks the milestone.
2. Conservation Invariants: Exact atom, charge, and first-law energy conservation asserted across every reaction, phase transition, transfer, rupture, spill, and atmospheric handoff.
3. Determinism & Neutrality (§28.8): Bit-identical results across repeat runs, secondary processes, and differing architectures. Reaction-ID permutation remains physically equivalent within numerical tolerance.
4. Equilibrium & Le Chatelier Properties: Property-based testing asserting that increasing a product’s partial pressure shifts reaction extent toward reactants for every reversible reaction.
5. Catalyst Invariance: A catalyst increases reaction rate ($r_f, r_r$) but never shifts the equilibrium constant ($K$).
6. Electrochemical Consistency: The thermodynamic bridge $\Delta G^\circ = -nFE^\circ$ round-trips consistently across all standard reduction potentials.
7. Faraday Accuracy: Ideal electrochemical cells match theoretical mass transport ($m = ItM/zF$); non-ideal cells account for current efficiency $\eta_I$ and side-products.
8. Hazard Fairness: Every avoidable lethal scenario must possess a prior, actionable, scientifically honest warning path. No test may pass by inventing human senses.
9. Throughput Prediction: Continuous industrial processes display theoretical stoichiometric ceilings alongside actual flow limits, conversion fractions, and mechanical losses.
10. Science Visibility & Epistemic Boundaries: Unobserved simulation truth cannot leak into names, tooltips, or achievements. Every displayed sentence traces back to a committed ScienceEvent.
11. Kinetic Validity Envelopes: Arrhenius rate models execute within documented temperature/pressure envelopes; out-of-envelope states flag warnings rather than yielding invalid outputs.
12. Material Ownership & Durability: Interrupted transfers, unloads, crashes, and reloads preserve single-owner accountability and causal event ordering.

---

Formative Playable Acceptance Protocol (§36.9)

Before expanding the chemical catalogue in C6, a formative playtest with at least five first-time players across diverse chemistry backgrounds must pass the following acceptance gates:

• Fire Discovery: At least 4 of 5 players create fire, find its after-action run entry, and name a feasible next experiment within 20 minutes without facilitator instruction.
• Causal Comprehension: On both an early success and a failed run, at least 4 of 5 players can explain what changed, cite supporting evidence, identify uncertainties, and choose a logical next action without guessing hidden formulas.
• Session Continuity: A player can safely pause, resume an interrupted 20–30 minute session, recover their intent from the laboratory notebook, and resume progress without duplicating work.
• Incident Recovery: A player can diagnose a seeded conveyor blockage, handle an unassayed retained sample, and recover from a destroyed apparatus using current-tier tools within scenario budgets.
• Pacing & Idleness: No compulsory idle waiting interval may exceed 60 seconds without offering a meaningful concurrent observation or task. Scientific rate constants may never be inflated to pass.
• Accessibility Equivalence: All progression tasks must remain achievable with colour discrimination disabled, audio muted, and strong screen camera effects turned off.

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Technology Tiers & Bootstrap Spirals (Masterplan §38)

Progression in Voxamine is structured around 21 technology tiers (T0–T20). Rather than a rigid tier ladder where higher tiers replace lower ones, the game operates as a series of interlocking bootstrap spirals where advanced capabilities loop back to upgrade foundational systems.

T0  HAND ─────────────────────────────────────────────────────┐
     │ wood, stone, clay, sand, fibre, water                   │
     ▼                                                         │
T1  FIRE  ~900 K ──────────────► ash ──► POTASH ────┐          │
     │ charcoal (pyrolysis)                          │         │
     ▼                                               │         │
T2  CERAMIC  ~1050–1200 K                            │         │
     │ crucible, retort, brick, pipe                 │         │
     ▼                                               │         │
T3  LIME  ~1300 K ──► mortar ──► better kilns        │         │
     │ CaO, Ca(OH)2, flux, limewater test            │         │
     ▼                                               │         │
T4  COPPER  ~1350 K + forced air ◄───────────────────┼─────────┘
     │ malachite → CuO → Cu                          │       (bellows need
     ▼                                               │        no metal)
T5  BRONZE  composition-dependent casting range      │
     │ Cu + Sn.  TOOLS.                              │
     │                                               │
     ╞═══════════════ MVP CUT LINE (§36.6) ══════════╪═══════════════
     │                                               │
     ▼                                               ▼
T6  GLASS  ~1400 K ◄──────── soda ◄──── T8  ALKALI & SALTS
     │ transparent vessels, tubing, LENSES           ▲
     │                                               │
     ├──────────────► T9  ACIDS ────────────────────┘
     │                 │ H2SO4, HCl, HNO3
     ▼                 │
T7  IRON & STEEL       │        T10  OPTICS & INSTRUMENTS
     ~1500-1800 K      │              │ lens, microscope, thermocouple,
     │ needs refractory│              │ balance, barometer
     │                 │              │
     └────────┬────────┴──────────────┘
              ▼
T11 ELECTRICITY ──── magnet + wire + motion = INDUCTION
     │ generator, motor                      ▲
     ▼                                       │
T12 ELECTROCHEMISTRY                         │
     │ cells, batteries, ELECTROLYSIS        │
     ├── electrorefining ──► pure Cu ────────┘   ◄── BOOTSTRAP SPIRAL
     │
     ▼
T13 REACTIVE METALS   Al, Na, Mg, Cl2, pure O2/H2
     │
     ▼
T14 ADVANCED MATERIALS  alloy steel, refractories, Si, Ti
     │
     ▼
T15 CRYOGENICS & VACUUM  liquefaction, air separation, high vacuum
     │
     ▼
T16 SUPERCONDUCTORS  Nb-Ti, Nb3Sn ──► high-field magnets
     │
     ▼
T17 FUSION FEEDSTOCK  D2O/D + lithium blanket ◄── isotope separation
     │
     ▼
T18 PLASMA: UNSTABLE  first D-D confinement, loss events, diagnostics
     │
     ▼
T19 PLASMA: STABLE  coupled control, declared Q_plasma target
     │
     ▼
T20 SPACE  propulsion, closed-loop life support, the voyage

The Three Core Bootstrap Spirals (§38.8)

1. The Copper Purity Spiral: Raw smelted copper contains arsenic, iron, and oxide impurities that lower electrical conductivity. Smelting yields wire suitable for crude dynamos; dynamos generate electric currents for electrorefining; electrorefined copper ($>99.99%$ purity) drastically lowers resistance, enabling high-performance generator windings and transformers.
2. The Vessel Refractory Spiral: Low-fire clay kilns ($1050\text{ K}$) allow the calcination of limestone to quicklime ($CaO$). Lime mortar and refractory clays enable higher-temperature kilns ($1350\text{ K}$) capable of smelting copper. Forced air and blast furnaces enable iron reduction ($1500–1800\text{ K}$), which in turn produces steel tools and refractory crucibles.
3. The Acid/Alkali Spiral: Roasting metal pyrites generates sulfur dioxide off-gas; lead-chamber condensation yields sulfuric acid ($H_2SO_4$); sulfuric acid leaches rock salt to yield hydrochloric and nitric acids, which enable hydrometallurgical extraction of rare minerals.

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Post-MVP Horizons (C8–C17)

Masterplan §36.8 and Part II (§35 & §38) project the technology tree beyond the initial copper-and-steam MVP toward modern industrial synthesis, fusion power, and space travel.

C8 — Laboratory Glassware (Tier T6)

• Soda-lime and borosilicate glassworking, controlled thermal annealing.
• Chemically inert, transparent reaction vessels that upgrade optical observation quality in the laboratory notebook.
• Fractional distillation columns and Liebig condensers for separating volatile fractions.

C9 — Aqueous Solution Chemistry (Tier T8)

• Solvation thermodynamics, hydration enthalpies, and ionic precipitation equilibria.
• Rigorous pH calculations under non-ideal conditions using Debye–Hückel and extended Pitzer activity models.
• Hydrometallurgical leaching, selective dissolution, and fractional crystallisation.

C10 — Mineral Acids (Tier T9)

• Industrial synthesis of sulfuric ($H_2SO_4$), nitric ($HNO_3$), and hydrochloric ($HCl$) acids via the lead chamber or contact processes.
• First-class chemical corrosion mechanics: wall passivation, containment etching, and acid-resistant alloys.

C11 — Electrochemistry & Electrolysis (Tiers T11–T12)

The single largest technological unlock in the game (§28.6).

• Primary galvanic cells, lead-acid accumulator batteries, and chemical voltmeters.
• The chlor-alkali process ($2NaCl + 2H_2O \to 2NaOH + Cl_2 + H_2$).
• Molten salt electrolysis (the Hall–Héroult process for aluminium extraction).

C12 — Electromagnetics & Power Distribution (Tier T11)

• High-purity electrorefined copper closing the positive feedback loop: higher purity $\to$ lower resistivity $\to$ more powerful dynamos and electric motors.
• AC transformers, polyphase power grids, and transmission line heat dissipation.

C13 — Reactive Light Metals (Tier T13)

• Reduction of elements that fire and carbon cannot liberate: metallic aluminium, magnesium, sodium, and calcium.
• Liquefaction and cryogenic storage of pure gaseous oxygen, hydrogen, and nitrogen.

C14 — Hydroponics & Closed Agricultural Loops (Tier T14)

• Precision plant nutrition: nitrogen fixation (Haber–Bosch), phosphate recovery, and trace mineral balance.
• Flue-gas carbon dioxide scrubbers routing industrial emissions into greenhouse enrichment atmospheres (§33).

C15 — Advanced Materials & Cryogenics (Tiers T14–T16)

• High-grade converter steel, high-alumina and zirconia refractories, and chemical vapour deposition.
• Superconducting coils (NbTi, YBCO), liquid helium cryostats, and ultra-high vacuum (UHV) pumping trains.

C16 — Stellarator Fusion Plasma (Tiers T17–T19)

The scientific summit of the terrestrial game (§35.2):

• C16a (Unstable Plasma): Constructing the twisted 3D modular coil set, vacuum vessel, and magnetic diagnostics. Initial plasma discharges suffer thermal disruptions, impurity radiation, and turbulent heat loss.
• C16b (Steady-State Confinement): High-speed real-time feedback tuning of auxiliary heating (neutral beam injection, ion cyclotron resonance) and pellet fuelling to suppress neoclassical transport and achieve sustained $Q_{\text{plasma}} > 1$ burning plasma conditions.

C17 — The Voyage (Tier T20)

The ultimate culmination (§35.3):

• Constructing an interstellar exploration vessel powered by aneutronic fusion.
• Zero-margin life support where life, agriculture, and industrial maintenance operate under absolute, irreversible conservation of mass.

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Technical Performance Budgets (§36.7)

Physical fidelity is never preserved by dropping simulation accuracy. If performance constraints are exceeded, simulated scope is curtailed (e.g., through aggressive vessel quiescence) rather than corrupting thermodynamic rigor.

Metric	Budget Target	Implementation Strategy
Simulation Tick	Fixed 20 Hz (50 ms)	Completely decoupled from the rendering frame rate; executed on background worker threads.
Active Vessels	$\le 256$ active	Rigid quiescence detection puts non-reacting, thermally equilibrated vessels to sleep.
Chemistry Solver	$\le 1.0\text{ ms}$ / tick	Amortized $\le 0.25\text{ ms}$ per rendered frame at 60 FPS; zero managed GC allocations.
Atmospheric Domains	$\le 64$ active	Conservative domain clustering, spatial envelope bounds, and seamless handoff to the regional ledger.
Conveyor Items in Flight	$\le 4096$ items	Compact struct representations with spatial bucket hashing; zero GameObject instantiation per item.
Power Network Solve	$\le 0.2\text{ ms}$ / tick	Sparse linear solvers for mechanical shaft torque and electrical distribution grids.
Managed Allocations	0 bytes	Zero GC allocations per tick during steady-state chemistry, vessel execution, and transport.
Save File Footprint	$\le 64\text{ MB}$ compressed	Compact binary diffing for world modifications; science event streams are append-only and deduplicated.

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Further Reading

• Masterplan (design/masterplan): The complete authoritative design document.
• System Maps (architecture/system-maps): Dependency graphs across Unity assemblies and scientific domains.
• Chemistry Foundations (science/chemistry-foundations): Fundamental simulation contracts, thermodynamics, and kinetic equations.
• Chemistry Sources (science/chemistry-sources): Empirical citations, NIST data tables, and validation error bounds.
• The Playthrough (concepts/the-playthrough): The intended player experience from hour 0 to hour 100+.
• Author an Ore Assay (contributing/author-an-ore-assay): Worked example implementing C2 assay and honest error bars.
• Author Atmospheric Enclosures (contributing/author-atmospheric-enclosures): Worked example implementing C3 enclosure scans and ventilation sinks.
• Author Science Narratives (contributing/author-science-narratives): Worked example implementing C1/C5 after-action reading-level bounds.