shipped / October 8, 2026
City 2026: a low-poly SimCity 2000 clone, decompiled and rebuilt by Opus 5.5 in a browser tab
score subagents: 27
Einar Andersson gave Opus 5.5 one prompt and a zip of the original SimCity 2000. The agent ran Ghidra on the PowerPC binary, translated it function by function with 27 subagents, and had the game running in his browser in about two hours. Then it built an emulator harness to prove the game logic matched, 10,000 game days deep.
Built by Einar Andersson with Claude Opus 5.5 and GPT Image 2.
see the announcement on Hacker News →demo
What it is
City 2026 is SimCity 2000 in a browser tab, drawn low-poly. The page says "Loading…" and then "Click to start," and that is the whole front door. Behind it is, in the maker's words, "a clone of simcity 2000 I (using Opus 5.5) built over a few days." A "full replica of game logic," not a tribute. The original rules, zoning, budgets and disasters, running in WebGL.
He added a few things the original did not have: smog, depth of field and environmental sounds, "to make it a bit more immersive without killing the original nostalgic vibe." If it runs slow, depth of field is on by default and Options > Display turns it off. That was his one reply in the thread.
How it was built
Einar Andersson is the technical co-founder of SeenThis, in Sweden, and the person behind dator.dev, a page of side projects like a browser Quake III map editor. His GitHub bio: "thank you, computer."
The whole story is in his Hacker News post. It started with a single prompt: "create a typescript webgl low-poly version (full replica of game logic) of simcity 2000," with a zip of the original game attached for inspection. Opus "decompiled it using Ghidra and started translating the old native PowerPC code function-by-function." Then: "After about 2 hours, using 27 subagents, i had a running version in my browser."
The verification step is our favorite part. He followed up with "make sure all aspects of the game is implemented correctly and accurately," and the agent chose its own method: it picked up the Unicorn PowerPC emulator, wrote "a harness with faked Mac system calls in Python," and ran the original and the port side by side for 10,000 game days until they produced "an identical game state."
After that, "it has basically just been polishing." The 3D and vector assets are generated with code by Opus, the bitmaps by GPT Image 2. The music and sounds are not AI at all, "because all AI audio models i've tried sound terrible." They are CC-licensed, with music by Kevin MacLeod.
Why we picked it
Because the surprising part is not that an agent wrote a city builder. It is that, asked to be accurate, it reached for an emulator and a 10,000-day replay instead of a shrug. That is a test plan most of us would not have written for ourselves.
And because of the reason he gave: "I created this because I wanted it and to see how capable Opus 5.5 was." Thank you, computer.
Shipped is Accept All's daily pick of things people build with AI, written by MK. We are not affiliated with Einar Andersson; the work and the credit are theirs, so go tell them it's good. Older: A Walkable History of Art: 82,139 paintings from Wikipedia, hung in 3D rooms you walk through.