Levelsio got Battlefield 1942 running in the browser with Claude Code

Pieter Levels (@levelsio) has put Battlefield 1942 on the web at bf1942.pieter.com: the free 2002 demo, with online multiplayer, in desktop Chrome or Edge. He posted it on November 2 and called it “probably my favorite game ever.”

His Quake and DOOM sites run on open-source engines other people built (FTE QuakeWorld, Q3JS and Odamex). He says Battlefield 1942 was much harder: “nobody had ever ported it and there was no open source engine for it, nor did the makers ever open source it.” He tried six months ago and mostly gave up. On November 2 he tried again with Claude Code, running Opus 5.5, with this prompt: “can you try port the BF1942 demo in this folder to web.”

57,000 functions and 100,000 lines of C

His launch post lists what Claude Code did that day. It disassembled the demo’s x86 machine code into 57,000 functions and translated each one into C, about 100,000 lines in all, then compiled that to WebAssembly with Emscripten. Around 300 Windows and Direct3D calls were rewritten for WebGL 2 and OpenGL, and he and Claude Code built a network layer so the game reaches his server over WebSockets. One translated line: mov eax, [esi+0x110] becomes eax = READ32(esi + 0x110). “I have no idea what any of this means btw,” he added.

On launch day the server’s 16-player cap filled up, and about ten minutes later he posted “Fixed now 64!” On November 3 he added Wake Island, the map with planes, then listed the server for the original game as well: “Playable both by real BF1942 clients and our own web-based client.”

What it takes to join

No account; you type a name. The first load is about 362 MB: 258 MB of game data, then 104 MB for Wake Island. On November 3 we joined a US vs Japan match on Wake Island. The site calls itself an unofficial, non-commercial fan project, not affiliated with EA or DICE.

The flight sim came first

His AI-made games go back to February 22, 2025, when he asked Cursor to “make a 3d flying game in browser with skyscrapers.” That became fly.pieter.com, which still bills itself as “100% made with AI.” On March 11, 2025, he posted that it had gone “from $0 to $1 million ARR in just 17 days” and that 320,000 people had flown in it.

In April 2025 he announced the winners of his 2025 Vibe Code Game Jam: more than 1,000 games submitted, with Andrej Karpathy and mrdoob on the jury. He wrote that “the vast majority of people participating never made a game before.” The 2026 Cursor Vibe Jam required at least 90% of the code to be written by AI. Its gold winner, A Game About Capybaras Delivering Food, is on the wall too.