Game Modes

ReflexGates

The primary game mode. A side-scrolling gate challenge where oscillating apertures appear on vertical walls — navigate the cursor through each gate before the scroll catches you.

Key properties:

• Fixed 60Hz timestep with accumulator-based catch-up
• xorshift32 RNG seeded per run for platform-stable generation
• FNV-1a 64-bit hashing for run identity — same seed + mode + mutators = same RunId everywhere
• Deterministic seed produces identical levels every time

The simulation interface

IGameSimulation is a two-method contract. New game modes plug in without touching the engine core:

1. Reset(uint sessionSeed) — initialize or re-initialize the simulation with a deterministic seed
2. FixedUpdate(long tick, float dt, in PointerInput input, List<GameEvent> events) — advance the simulation by one fixed timestep, emitting events into the provided list

The DeterministicLoop drives the simulation at 60Hz using an accumulator pattern. It tracks host time, accumulates delta time, and calls FixedUpdate one or more times per frame to catch up (capped at MaxStepsPerFrame, default 5). After all fixed steps, it computes an alpha value for smooth rendering interpolation between simulation states.

Level generation

Levels are generated through a pipeline:

1. ILevelGenerator produces a LevelBlueprint from a seed
2. The MutatorPipeline transforms the blueprint through an ordered fold of IBlueprintMutator instances
3. The final blueprint is used by the game mode simulation

The LevelGeneratorRegistry resolves generators by game mode, and the MutatorRegistry resolves mutators by MutatorId. Both are factory-based for extensibility.

ReflexGates configuration

ReflexGateConfig controls all tuning knobs for a level. Default values:

Parameter	Default	Description
PlayfieldWidth / Height	1920 x 1080	Virtual coordinate space
GateCount	12	Number of gates per level
ScrollSpeed	70 px/s	Auto-scroll rate (~83 seconds per clean run)
BaseApertureHeight	200	Starting gap height (shrinks to 100 by the last gate)
BaseAmplitude / MaxAmplitude	40 / 350	Oscillation range (gates 1-4 nearly stationary, 9-12 hard)
BaseFreqHz / MaxFreqHz	0.15 / 1.2	Oscillation frequency ramp
CenterScore / EdgeScore	100 / 50	Points for passing through the center vs. the edge of a gate
ComboThreshold	3	Consecutive passes before a ComboUp event fires

Scoring

When the cursor passes through a gate, the score is interpolated between CenterScore (100 for a dead-center pass) and EdgeScore (50 for a pass at the aperture edge). Missing a gate resets the combo streak to zero.

The SessionController tracks a ScoreBreakdown built from ScoreDelta records. Each delta is tagged with a ScoreComponentId (GateScore or MissPenalty) and the combo count at that moment. The breakdown enforces a conservation invariant: the sum of all component totals equals the session total.

Session lifecycle

The SessionController is a state machine with three phases:

1. Ready — initialized with a seed and gate count, waiting to start
2. Playing — elapsed timer running, processing GameEvent emissions from the simulation
3. Results — level complete, final SessionResult available (immutable record with score, combo, gate results, verification hash)

Replay verification

DMTE includes a full replay system. The ReplayRecorder captures quantized input samples every tick during live play. At session end, it produces an immutable ReplayEnvelope containing the full input trace, run identity, and verification hash.

The ReplayVerifier can replay an envelope through a fresh IGameSimulation instance, comparing the event stream hash, final score, and max combo against the envelope’s claims. If any value diverges, the replay is invalid — proving the determinism guarantee holds.