Harbor Run. The white boat is the test bot, the red one is the AI rival. Recorded in the engine on an M4 Pro Mac, Oct 5 2026.

Arcwright is a game engine that plays its own games.

I don't write code. I direct AI agents, and they build each game inside the editor while I watch. Then a bot plays it through the real controls and writes up what happened. Nothing counts as done until that report says it works.

One email when the first builds go out. Nothing else.

Automated tests
479
Oct 7
Castaway, bot runs won
10 of 10
proof report, Oct 5
Castaway, median frame
16.67 ms
M4 Pro, 60 Hz display
Replay checkpoints matched
217 of 217
Castaway golden replay, Oct 7

The agents work in the editor, in front of you.

Every object they add shows up in the scene list as it happens. You can stop them, change anything by hand, or undo any step. Nothing happens off-screen.

The Arcwright editor with Harbor Run open: the scene list on the left, two speedboats at a jetty at sunset in the viewport, the inspector on the right
Harbor Run open in the editor on an M4 Pro Mac, Oct 7. A few labels are blurred.

Every build ends with a report.

Castaway started as one sentence: wash up on an island, gather driftwood, light a signal fire before night. Agents built it in the editor. Then the bot played it ten times on ten different seeds. This is part of what came back.

Castaway, seed 1. The bot lights the fire with 87 seconds of daylight left.

Proof: Castaway build deb6469 · Oct 5, 18:23 · checked in 16 s

Game Plan tests10 of 10 pass
Bot playthroughswon 10 of 10
Frame timemedian 16.67 ms, p95 17.84 ms
GPU per frame11.50 ms
 155.5 s  got Driftwood_3
 180.6 s  got Driftwood_2
 180.6 s  heading for Signal_Fire
 215.8 s  won: Signal fire lit with
          87 s of daylight left.

When a run fails, the report names the object that caused it. Building Circuit, the bot found that trigger zones ignored rotation in every game, and that a wedged car could never reverse. Both were fixed in the engine, so every game got the fix.

Three games so far, each one bot-tested.

A man stands at a bonfire on a hill at dusk, palm trees behind him

Castaway

Survival on an island. The engine had no fire, no sunset and no way to spread trees over a beach. This game needed all three, so they went into the engine, and every later game can use them.

10 of 10 bot wins · fastest 214 s · 59 objects, 44 of them palms

Circuit

A race against an AI driver. The test bot had never driven a car, so it learned to: walk to the car, get in, follow the road. Its first attempt cut straight across the grass.

1,184 m lap · about 110 km/h · 5 of 5 races finished

A jetty at dusk with two speedboats moored, a hill behind

Harbor Run

Boat racing. The ocean existed, but nothing could float on it. Boats now ride the same waves the renderer draws, on the same clock, which is why the result doesn't change between machines.

Seed 1 finishes at 2:12.78 on the Mac and 2:12.78 on the Steam Deck

A pitch-dark office corridor lit only by a circle of flashlight

Lights out in progress

Next up: a horror game in endless yellow offices. The lights flicker, then go out, and all you have is the flashlight on your gun. Its shadows are real, cast from the beam. First playtest was on Oct 7, on a Steam Deck controller.

Not bot-tested yet · the creature that hunts in the dark is still being built

Objects are made inside the engine.

Give it a reference sheet and it builds the object, then compares its own renders to the reference from each side and keeps adjusting. Below: a car from one sheet. The red line is the reference outline.

Car, front
front
Car, side
side
Car, top
top
Car, three-quarter
three-quarter
The built car with the reference outline in red, side and three-quarter views
A panelled door
door
A wooden dresser
dresser
Castaway running on a Steam Deck
Castaway on a Steam Deck.

Made on a Mac. Plays on a Steam Deck.

The first frame on the Deck took a whole second, because skinning the character ran on the CPU. Moving it to the GPU took it to 60 fps, about 58 with shadows on.

Finish times on two machines
Mac (Apple ARM)Steam Deck (AMD x86)
Castaway, seed 1218.8 s218.8 s
Harbor Run, seed 12:12.782:12.78

Windows player builds come from the same source and currently run under Proton on the Deck.

Build log

Arcwright is built by one person who doesn't code, directing AI agents. Nothing merges until the tests pass. 385 commits as of Oct 7.

  1. First commit at 5:27 am. Before 8 am an agent had built a stealth level live in the editor: guards with vision cones and flashlights, a yard, an escape.

  2. Castaway, Circuit and Harbor Run built. The bot wins all three. Fire, sunsets, cars and boats added to the engine along the way.

  3. Ported to Steam Deck. The same three games run at 60 fps, and finish times match the Mac to the hundredth of a second.

  4. 479 tests. First playtest with a Deck controller in hand. Named it Arcwright.

Where it stands

Working
Building in the editor, bot playtests, replays, the object maker, Mac and Steam Deck players.
In progress
Realistic people and faces, creatures, cutscenes, save games.
Not yet
A public release, online multiplayer, consoles.

Founding creators get in first.

  • Early access to the editor.
  • A say in what gets built next.
  • Updates as it ships, from the build log.