Drift — Round 2 Gameplay Specification Evaluation

Executive Summary

No changes to spec since Round 1. Drift remains a geometric masterpiece combining mathematical rigor with sophisticated audio design. The single minor gap (hot swap phase chain byte format) is identical to SynthFence and equally non-blocking.

Round 2 Re-Confirmation: All Round 1 scores hold. The module’s exclusive strengths (bearing-to-frequency mapping, three-bearing triangulation as core loop, audio-only mode as accessibility feature) remain exemplary. PASS threshold (40+) maintained decisively at 49/50.

Round 2 Scoring (10-Criterion Rubric)

#	Criterion	R1	R2	Change	Status
1	OODA/Core Loop Clarity	5/5	5/5	—	✓ Perfect atomic unit (8–12 second OODA cycle)
2	Cell Architecture Completeness	5/5	5/5	—	✓ Five cell types fully specified with handlers
3	Key Mapping Exhaustiveness	5/5	5/5	—	✓ All 30 keys mapped (left grid + numpad cardinal directions)
4	PSG Audio Specification	5/5	5/5	—	✓ Geometric audio design (bearing sonar, harmonic feedback, threat pulse)
5	Screen Wireframe Coverage	5/5	5/5	—	✓ Five detailed wireframes, all 80×25 compliant
6	Hot Swap Integration	4/5	4/5	—	✓ Strong campaign but phase-chain byte format not specified
7	Mission Template Specificity	5/5	5/5	—	✓ Four archetypes with procedural variation and threat scaling
8	Session Walkthrough Depth	5/5	5/5	—	✓ Complete 26-turn session with turn-by-turn annotation
9	Platform Constraint Adherence	5/5	5/5	—	✓ All hardware/software constraints respected
10	Engineering Readiness	5/5	5/5	—	✓ C engineer can implement directly (triangulation geometry is clean)
	TOTAL	49/50	49/50	—	STRONG PASS

Detailed Analysis: No Changes Since Round 1

1. OODA/Core Loop Clarity: 5/5

Atomic unit well-defined: 8–12 second OODA cycle. OBSERVE (listen to bearing), ORIENT (interpret angle), DECIDE (move antenna or lock bearing), ACT (press key). Irreversibility: antenna moves permanent, bearings locked until triangulation. Timing precise: bearing 0° = 200 Hz, bearing 90° = 500 Hz, bearing 180° = 800 Hz. Turn cost explicit (antenna move = +1 awareness, bearing lock = +1 awareness, INFO query = +0).

2. Cell Architecture Completeness: 5/5

Five cell types (SIGNAL_SOURCE_CELL, ANTENNA_CELL, TRIANGULATION_CELL, SURVEILLANCE_THREAT_CELL, FIELD_CELL) defined in pseudo-C with CELL_TYPE macros. Each has state fields, ON_* handlers, ON_DISPLAY. Struct layout inferred directly. Memory-safe (uint16_t for coords, uint8_t for angles, confidence %).

3. Key Mapping Exhaustiveness: 5/5

Left-hand function keys fully mapped: CAR (next antenna), CDR (prev antenna), CONS (lock bearing line), EVAL (confirm/intercept), APPLY (amplify, +15dB, +3 awareness), BACK (SILENT mode, pause activity, decay awareness), NIL (reset all bearings, +2 awareness cost), QUOTE (bookmark triangulation), INFO (query bearing numeric, +0 awareness). Right-hand numpad: 8/2/4/6 for antenna movement (N/S/W/E cardinal directions), 1/2/3 for quick antenna select. All 30 keys accounted for. Lisp grammar intact.

4. PSG Audio Specification: 5/5

Three voices fully specified with frequency/amplitude tables:

Voice 1 (bearing sonar): 0° = 200 Hz, 90° = 500 Hz, 180° = 800 Hz, 270° = 500 Hz, interpolated for all 360°. Signal strength modulates tone (80+ dB = pure, 60–80 = fuzzy, 45–60 = buried, <45 = inaudible). Multipath ghosts (threat 5+): three tones with 100–300ms delays.
Voice 2 (triangulation harmony): Major triad on excellent geometry (±0.5 cells error), dissonance on poor geometry (±5+ cells).
Voice 3 (threat beat): 0–20 awareness = silent, 21–40 = 1 Hz beat (faint), 41–60 = 2 Hz (dissonant tritone), 61–80 = 3–4 Hz (loud), 81–100 = chaotic noise.

Envelope timing specified: 500ms dissonance on watchlist, 1s on position limit, 2s on margin call. Audio-only mode mastery documented (screen off, button feedback tones: 8=rising, 2=descending, 4=left pan, 6=right pan).

5. Screen Wireframe Coverage: 5/5

Five detailed ASCII wireframes, 80×25 format, amber on black: (1) Mission Board, (2) Triangulation Display, (3) Move-to-Target Phase, (4) Bitmap Mode (optional grid visualization), (5) Audio-Only Mode. All include action bar and status row. Compliant with platform constraints.

6. Hot Swap Integration: 4/5

Strong campaign structure: SIGNAL HUNT (multi-phase): Phase 1 DRIFT (locate source via triangulation) → Phase 2 SHELLFIRE (manage frequency bands, extract payload, window opens only if DRIFT succeeded) → Phase 3 ICE BREAKER (intrude network, retrieve encryption keys).

Minor Gap: Phase chain serialization mentioned but byte-level format not specified. What gets passed from Phase 1 to Phase 2?

Likely: antenna_positions[3][2], locked_bearings[3], triangulation_confidence, final_threat_level
Round 1 Recommendation: Document the struct layout
Round 2 Status: Gap persists (spec unchanged)

Impact: Non-blocking. Struct can be inferred from narrative. Suggest: add concrete C struct in design review or SHELLFIRE integration spec.

7. Mission Template Specificity: 5/5

Four contract archetypes:

CORPORATE CALL INTERCEPTION: Threat 2, 26-turn window, 1,400 ¤, civilian awareness baseline
DISTRESS BEACON RESCUE: Threat 3, 22-turn window, 1,800 ¤, time-critical, higher initial awareness
PIRATE FREQUENCY SWEEP: Threat 3, 20-turn window, 2,400 ¤, moving target (source drifts on patrol route)
MILITARY INSTALLATION PROBE: Threat 5, 18-turn window, 4,500 ¤, multipath environment (ghosts increase confusion)

Procedural variation: LFSR seeds source location (x,y) on 16×10 grid, signal strength formula (100 − distance × 3.5 dB), threat level affects awareness decay rate and hunter spawn threshold. Window sizes scale with threat.

8. Session Walkthrough Depth: 5/5

One complete session (“THE FIX,” Threat 2, 26-turn window, operator “Rep 12”) with minute-by-minute and turn-by-turn annotation. 22 discrete scenes/turns: boot/briefing (0:00), antenna init (0:45), antenna A repositioning (1:15–1:50), first bearing locked (1:50), antenna B repositioning (2:30–3:00), second bearing locked (3:00), antenna C repositioning (3:35–4:45), move-to-target phase (4:45–5:30). Keystroke-by-keystroke: “numpad 6, 6, 6” for three east moves. Audio state changes (Voice 1 rising, Voice 1 stabilizing, Voice 2 glissando, Voice 2 triad, Voice 3 escalation). Awareness escalation pattern explicit. Tight margin (4 turns buffer). 22 turns annotated turn-by-turn.

9. Platform Constraint Adherence: 5/5

80×25 display respected. 30-key layout (14 function + 16 numpad). Lisp grammar preserved. Cell pool: five cell types, each <64 bytes. YM2149 3-channel (Voice 1 bearing sonar, Voice 2 harmonic feedback, Voice 3 threat pulse). Cipher voice integrated. Grid-based geometry (16×10 grid). Nosh API delegates to display/sound. Audio-only mode respects YM2149 constraints (no stereo, panning inferred from pitch modulation and button feedback tones).

10. Engineering Readiness: 5/5

C11 engineer can implement directly. Bearing-to-frequency mapping is deterministic (freq = 200 + bearing × 3.33 Hz). Signal strength formula explicit (100 − distance_cells × 3.5 dB). Triangulation geometry is standard 2D line-of-sight (three bearing lines, solve for intersection, compute confidence from angle between lines). Hunter spawn/movement straightforward (spawn at awareness >= 50, move toward nearest antenna every 2 turns, interception on collision). Audio callback updates Voice 1 pitch, Voice 2 chord, Voice 3 beat tempo each frame. Awareness decay on BACK press (enters SILENT mode, awareness −= 1 per turn until exiting). All state machines explicit. Mission templates instantiate via seed + threat level lookup table.

The Single Minor Gap (Harmless, Identical to SynthFence)

Hot Swap Phase Chain Serialization (4/5):

Round 1 feedback: “phase chain serialization for hot swap” mentioned but not byte-level format.

Round 1 Recommendation:

typedef struct {
    int16_t antenna_final_positions[3][2];  // Where they ended up
    uint16_t bearing_angles[3];             // Locked bearing values
    uint8_t triangulation_confidence;       // 0–100
    uint8_t final_threat_level;             // For SHELLFIRE awareness baseline
} PhaseChainDriftState;

Round 2 Status: Spec unchanged. Gap persists.

Severity: VERY LOW

Not a blocker for implementation
Drift can be coded, tested, shipped without this detail
SHELLFIRE phase 2 can verify Phase 1 success (did operator triangulate, or guess?)
Struct can be finalized in integration testing or SHELLFIRE spec

Drift’s Exclusive Strengths (Persisting from Round 1)

Geometric rigor with audio as primary sense: Bearing-to-frequency mapping (0° = 200 Hz, 90° = 500 Hz, 180° = 800 Hz) is mathematically clean. Players learn to estimate direction from pitch, not visual cues. Not a gimmick; it’s a real skill. Audio-only mode enables players with visual impairments to play at mastery level. Inclusive design.
Signal strength modulation for information depth: Voice 1’s tone quality (pure at 80+ dB, fuzzy at 60–80, buried at 45–60) teaches signal-to-noise understanding. Multipath ghosts (threat 5+) add realism—three tones at staggered delays simulate RF reflection. Player learning to filter the primary tone by temporal arrival is learning actual RF engineering concepts.
Three-bearing triangulation as core loop: Acquiring one bearing is easy (5 turns), two bearings still ambiguous (still 2 possible target points), three bearings locks it (convergence). Turn count to confidence progression (1 bearing = out of range, 2 bearings = ±2 cells error, 3 bearings = ±0.5 cells with major triad harmony) mirrors real triangulation geometry. Voice 2’s harmony quality (major = confident, diminished = poor) makes geometry feedback audible.
Threat scaling via awareness escalation: Unlike other modules (time pressure, margin calls), Drift’s threat is cumulative awareness. Operator movements make noise (RF emissions), queries are quieter. Awareness accelerates toward Hunter spawn (50 → 100), Voice 3’s beat tempo increases (1 Hz → 4 Hz → chaotic). Operator hears their own doom approaching. Final 4–5 turns under time pressure + escalating Voice 3 creates palpable tension.
Session walkthrough as pedagogical artifact: “THE FIX” shows not just gameplay, but operator learning curve. Turns 1–5: “No signal, antenna too far.” Turn 6: “First bearing acquired.” Turns 7–11: “Geometry ambiguous.” Turns 12–16: “Three bearings locked, major triad resolves, confidence 91%.” Operator understands the game’s system, not memorizing moves.
Campaign narrative via phase chain: SIGNAL HUNT (3-phase): Phase 1 (DRIFT) locates RF source → Phase 2 (SHELLFIRE) extracts encrypted payload (window opens only if Phase 1 completed) → Phase 3 (ICE BREAKER) retrieves keys to decrypt Phase 2’s payload. Operators understand why they swap (capability unlock).

Confidence Assessment

Spec Quality: Exemplary. Sets the standard for audio-visual integration and accessibility-first design.

Engineering Readiness: 5/5 — Geometry is clean (2D line-of-sight, no complex physics). Audio is event-driven. No blockers.

Estimated Timeline:

Cell handlers + signal geometry: 2 weeks
YM2149 voice callbacks (bearing-to-frequency): 2 weeks
Screen rendering + BITMAP mode: 1.5 weeks
Hunter AI + awareness decay: 1 week
Mission template instantiation: 1 week
Audio-only mode + button feedback: 1 week
Session testing + tuning: 1.5 weeks
Total: ~10 weeks for production quality

Risk Level: LOW — Triangulation solver is straightforward linear algebra (three lines, solve for intersection). Audio-only mode requires careful tuning but is non-critical for Phase 1 launch.

Minor Gap (Phase Chain Serialization): Does not impact prototyping. Resolve in SHELLFIRE integration review.

Verdict: PASS (49/50) — READY FOR SPRINT

Recommendation: Move Drift to implementation sprint immediately. The single minor gap (phase chain byte format) is design review caliber and should not delay coding. Suggest: address in SHELLFIRE integration spec or SIGNAL HUNT campaign document.

Note on Strengths: Drift’s accessibility-first design (audio-only mode with button feedback tones mapping to bearing angles) is exemplary. This approach should influence design of future modules. Audio-only gameplay is not a novelty feature; it’s genuine skill expression and inclusion.

END OF EVALUATION