platformer-game

name	platformer-game
description	Mario-style 2D platformer with stomp/bump/ability/gate/combo mechanics
artifact_kind	game
subtype	platformer
declared_verbs	[{"verb":"defeat","selector":"enemiesDefeated","success":{"op":"increase","path":"enemiesDefeated"},"required":true},{"verb":"collect","selector":"blocksUsed","success":{"op":"increase","path":"blocksUsed"},"required":true},{"verb":"unlock","selector":"gatesUnlocked","success":{"op":"increase","path":"gatesUnlocked"},"required":true},{"verb":"moveTo","selector":"player.x","success":{"op":"change","path":"player.x"},"required":true},{"verb":"traverse","selector":"comboChallenge","success":{"op":"truthy","path":"coverage.comboChallenge"},"required":false}]

Platformer Game

Mario-style 2D side-scrolling platformer. Player walks/jumps through level segments, stomps enemies, bumps question blocks for rewards, gains rule-changing abilities (double jump / dash / wall jump etc.), and uses those abilities to unlock gated routes. At least one comboChallenge combines jump with two of stomp/bump/ability/gate.

Overview

Genre conventions:

• Acceleration / friction, gravity, jump buffering or coyote time, recovery.
• Input-driven collision with platforms, hazards, rewards, and goals.
• First screen shows actor, controls, feedback, reward/risk; HUD updates score, health, objectives, win/fail, and progression.
• Canvas scales to viewport with max-width / max-height / aspect-ratio / height: auto; narrow windows must not crop the playfield.

Subtype identifier (subtype: platformer) goes in __GAME_META__ and triggers the PlatformerChecker validation pipeline at src/host/agent/runtime/game/platformer/PlatformerChecker.ts.

Generation Hints

This section is build-time inlined into game prompt assembly so the SKILL.md stays a single-source-of-truth reference for platformer generation guidance.

• Translate genre/reference into mechanics, not only visual skin.
• Platformers must include acceleration/friction, gravity, jump buffering or coyote time, recovery, and input-driven collision with platforms, hazards, rewards, and goals.
• Gameplay Mechanics Contract: implement a stompable enemy, a bumpable/question block, a movement/interaction-changing ability, an ability-gated route, and one comboChallenge that combines jump with at least two of enemy/block/ability/gate play.
• For subtype platformer, use exact shape gameplayMechanics: { enemies: [], blocks: [], abilities: [], gates: [], comboChallenge: [] }; each field is an array even when it has one item, never an object map.
• Fill stompable/defeatReward, bumpableFromBelow/reward/usedState, acquiredFrom/effect/unlocksRoute, requiresAbility/blocksAccessTo, requires/target. Use doubleJump, dash, shield, magnet, groundPound, or wallJump.
• For movement metrics like player.x, player.y, player.vx, player.vy, the expect MUST be one of "increase" / "decrease" / "change", never a numeric target. A numeric or boolean expect means exact final equality after the declared frames, only valid for counters like enemiesDefeated / blocksUsed / gatesUnlocked or boolean flags like abilities.doubleJump.
• Reachability steps must be short, deterministic, and locally true: use real snapshot paths such as player.x, player.vy, enemiesDefeated, blocksUsed, abilities.doubleJump, gatesUnlocked, routesUnlocked; do not expect score/progress/win/gate/ability changes unless that exact input window triggers live collision.
• For platformers, nearby authored smoke scenarios like reset('stomp'), reset('bumpBlock'), reset('gainAbility'), and reset('unlockGate') are better than long full-level treks, but they must still use live physics/collision.
• For platformers, runSmokeTest() proves gameplayMechanics with before/after snapshots: stomp enemy defeated plus player bounce/vy, bump block used/spawnedReward, ability changes, gate/route reachability after ability, and comboChallenge sequence.

Repair Hints

Failure Code	Hint
missing_gameplay_mechanics	Add gameplayMechanics to __GAME_META__ with enemies, blocks, abilities, gates, comboChallenge (each an array, never a map). Implement collision: stomp marks enemy defeated and bounces player.vy; bump marks block used and spawns the ability; ability changes movement; gate checks ability before route access.
gameplay_mechanics_without_runtime_evidence	Repair runSmokeTest() so it drives step() through stomp enemy, bump block, gain ability, unlock gate/route, and combo challenge — record coverage only after before/after snapshot changes prove each mechanic.
ability_gate_without_reachability	Make one ability change movement or interaction rules and unlock a real gated route. snapshot() should expose abilities and gate/route state, and runSmokeTest() must prove ability false → true followed by gate/route unreachable → reachable.

Other platformer-specific repair hints:

• For platformers, add/repair gameplayMechanics with enemies, blocks, abilities, gates, and comboChallenge, wired to real step() gameplay and runSmokeTest() before/after snapshot evidence.
• Platformer gameplayMechanics.enemies, blocks, abilities, gates, and comboChallenge must be arrays; do not repair them as { enemies: { ... } } or keyed object maps.
• If the full level path is too long, repair platformers with deterministic authored scenarios for stomp, bumpBlock, gainAbility, unlockGate, and comboChallenge using the live rules.
• Platformer coverage must prove stompEnemy, bumpBlock, gainAbility, unlockGate/routeReachableAfterAbility, and comboChallenge, with stateChanges for enemiesDefeated, player.vy/bounce, blocksUsed/spawnedReward, abilities, and gates/routes.

Snapshot Paths Reference

Platformer snapshots are expected to expose at least the following paths so progressPlan / reachability and runSmokeTest() coverage have stable selectors:

• Position / motion: player.x, player.y, player.vx, player.vy
• Combat counters: enemiesDefeated / defeatedEnemies (also matches stompedEnemies, stomps)
• Block interaction: blocksUsed / blocksBumped / blockHits / spawnedRewards
• Abilities: abilities.doubleJump, abilities.dash, abilities.shield, abilities.magnet, abilities.groundPound, abilities.wallJump, or under player.abilities.*
• Gates / routes: gatesUnlocked / routesUnlocked / reachableTargets, or gates.<id>.{open,unlocked,reachable}
• Coverage names (returned from runSmokeTest().coverage): coverage.mechanics, coverage.rewards, coverage.risks, coverage.stateChanges, coverage.gameplayMechanics, coverage.mechanicsEvidence, coverage.allLevelsReachable

Reference Examples

• Static mechanics check & runtime evidence assertions: src/host/agent/runtime/game/platformer/PlatformerChecker.ts
• Repair codes (failure pattern → hint): src/host/agent/runtime/game/platformer/repairCodes.ts
• Architecture audit & migration plan: docs/audits/2026-05-07-game-acceptance-architecture.md §5–§6