Play the engine.
many games, every one machine-verified before it shipped. Several are art-finished in the house woodblock style; the rest are honest engine slices — each one built to stress one capability end to end, playable in the browser and readable at the source. This is what “make a game with hayao” produces today.
Kintsugi — the flagship
The first real game, not a slice: a hand-authored, ability-gated, 30-room metroidvania in the woodblock style — machine-proven completable and softlock-free, with satisfying combat, multi-phase guardians, adaptive music, a plotted arc, and a map. Mend a shattered world with gold, seam by golden seam.
Art-finished showcases
The art bar for the engine slices — code-as-art in the woodblock style, static and deterministic, out of the sim's hash.
Physics & motion
One deterministic rigid-body core — stacks, ropes, CCD, restitution — reused across four very different games.
Rookspire
Rigid-body castles (stacks, planks, ropes) razed by a CCD cannonball — every castle proven to fall within its stone budget by a siege bot.
Brasswick
A brass-and-felt table from the same physics world — kinematic flippers, bumper-bells, CCD-tight geometry proven ball-bound (0 escaped frames).
Pinshine
Swept-circle collision (no tunneling at any speed), restitution proven energy-honest, every board proven clearable by an aim-search bot.
Vellgrove Rally
Understeer at speed, grass that punishes, cut-proof laps — braking into corners proven faster than flooring it.
Real-time action & AI
Fixed-step sims with hundreds of agents, character controllers, vision and lighting — each proven beatable by a scripted bot, not a promise.
Shard Ascent
Coyote time, jump buffering, dashes, corner correction, moving lifts. Every level is bot-proven beatable, deathless.
Sproutveil
Ability-gated exploration where every gate is machine-proven impassable without its ability — and the whole run bot-proven beatable.
Emberwake
Auto-fire, level-up builds, 160+ enemies on the Canvas backend — the full night is bot-proven survivable and the sim steps in 0.02ms.
Duskveil
A pattern DSL, 480+ live bullets, grazing, focus mode — every phase proven survivable by a predictive dodge bot.
Bramblefall
Flow-field pathfinding, 260+ units, a spear/cavalry/archer counter triangle — every counter edge is duel-proven and the war is bot-winnable.
Veilstep
Raycast vision cones, detection meters, noise, bushes — the full idol run is bot-proven doable with zero alarms, and the punishments proven real.
Palewood
A raycast-lit lantern, panned growls in the dark, fuel pressure that forbids camping — the night proven survivable, the dark proven deadly.
Puzzles & solver proofs
Pure Puzzle<State, Move> rules a search can exhaust — so every level ships with a machine proof it is winnable, and two reproduce human-ranked js13k winners.
Sokoban
The reference example: pure solver-provable logic + a scene-tree SVG view + undo. Every level is machine-verified winnable.
Seamfold
Sokoban with no outside — seams that shift you sideways, every level proven to NEED the fold (unsolvable without it). Reproduces Edge Not Found, js13k 2020 #2.
Gravewell
Collapse stars into black holes and sweep the debris in — every tap budget proven tight (par−1 is a proven loss). Reproduces Black Hole Square, js13k 2021 #9.
Emberfold
2048 as a solver-proven puzzle: no random spawns, just dealt embers and immovable stones that partition each slide. All 40 boards proven fusable to target, the minimum-slide par proven honest, the curve proven to ramp 2→11.
Thornspire
Card DSL, telegraphed intents, drafts between fights — tuned to a proven 17/20 pilot win rate, with drafting proven to matter.
Vantage
Telegraphed attacks, push chains that rewrite the enemy's future — a perfect defence is machine-proven possible, and doing nothing proven fatal.
Cadence Hollow
Move only on the pulse, foes dance in lockstep — the beat IS sim time, so even rhythm replays deterministically.
Glimmerfall
Cascade combos, spring-tweened choreography over an instant sim — 100 boards proven fair, targets proven reachable.
Systems, simulation & netplay
Procgen fairness proofs, economy pacing curves, and deterministic multiplayer — the sim's purity is what makes each of these checkable.
Hollowdeep
Procgen floors proven connected across 50 seeds, raycast FOV with map memory, bump combat — every dungeon bot-proven winnable.
Lumen Forge
DOM buttons flow through the deterministic input log; the whole pacing curve is simulation-verified.
Emberreign
Four meters, double-edged cards, story arcs — judgement proven to matter (19/20 vs 0/20 reigns) and every doom proven honest.
Fernclash
Sumo shoving on a fern ring — hot-seat or true lockstep netplay across tabs/machines, peers proven to agree bit-for-bit.
Poke the engine
Not games — single-mechanic labs. Each isolates one primitive with the knobs exposed, so you can see how a part behaves before you compose it into anything. This is the reference for “how do I use X?”; the games above are the reference for “how is a game structured.” Source: sandboxes/.
Physics Lab
Drop bodies into a bin and watch the constraint solver stack them. Knobs: SPACE drop, X box/circle, ↑↓ gravity, R clear. The createRigidWorld primitive, alone.
Particle Studio
A fountain of the PARTICLE_PRESETS; SPACE fires a big burst. Knobs: X cycles preset, ↑↓ count. Seeded, so the same run re-derives.
Camera Lab
Drive a dot; a Camera2D + CameraController chases it through a deadzone, smoothed, edge-clamped. Knobs: arrows move, Z/X deadzone, C smoothing.
Pathfinding Demo
Paint walls and watch astarGrid re-solve instantly. Knobs: arrows move cursor, SPACE wall, X goal, Z diagonal, R clear. Fully deterministic.
Juice Lab
Every EASINGS curve plotted at once with a marker sweeping along it, so you can see each one's character. Knobs: ↑↓ sweep speed, Z pause.
Procgen Lab
Seeded cellular-automata caverns via generateCave; the same seed always re-derives the same cave. Knobs: SPACE re-roll, ↑↓ fill %, X smoothing passes.