i built street fighter’s car smash on my phone, at the beach
A playable recreation of the car-smashing bonus stage from Street Fighter II: The World Warrior (1991), built from an iPhone with Claude Code. Fan work, sprites cut from arcade rips, no affiliation with Capcom.
how long did it take?
One day — 13 August 2026 — and about two hours of actual attention spread across it. I was at a beach in the south of France with my family for the rest of it. No laptop at any point.
what is it built with?
No game engine. Plain TypeScript and a hand-written software rasterizer drawing into a single 384×224 framebuffer — the arcade board’s resolution, which every other dimension is measured against. Eighteen normals, motion inputs for the specials, and a toggle that puts each special on its own button. Desktop and phone, keyboard and touch.
what goes wrong when an agent builds something visual?
Twice, the same failure. The first build was procedural — polygon car, puppet fighter, stage drawn in code. It looked nothing like Street Fighter II, so I fixed the horizon, the band heights, the palette, the HUD, the proportions. Every change measured closer to the reference. It still looked wrong.
Metrics improving while the side-by-side keeps looking wrong means the technique is wrong, not the tuning. Arcade art is hand-placed pixels; a polygon renderer makes flat fills. Cutting real sprites fixed it in one pass.
Then it repeated one level down: moves were matched to sprite frames by reasoning about the frames’ dimensions, so half the buttons drew the wrong thing. A bounding box does not identify a drawing.
A measurement that correlates with the thing you want is not the thing you want. An agent will optimise whatever you can measure and will never be the one to tell you the approach is wrong — by its own numbers, it is winning.
how do you review an agent’s work from a phone?
Checkpoints, not one reveal at the end. Three points, three questions:
- One still arcade frame, no gameplay. Does it look like SF2?
- The car and the damage model. Does smashing it feel good?
- The fighter and the moveset. Does it feel like Ryu?
Everything downstream inherits checkpoint one’s palette and proportions, so it is the cheapest place to be wrong. It is where the procedural build turned out to be unfixable rather than unfinished.
can you build a game from your phone?
Yes. Two things it takes. You need to know what good looks like — most of the work above was rejecting output and saying why, and taste does not come out of the agent. And the agent has to keep running while your screen is off, or this is just typing on a small keyboard.
That second part is what Yado does: it runs Claude Code or Codex in a cloud container on your own Claude or ChatGPT subscription, so a session survives you locking the phone. $19 a month. I build it — read the above knowing that.