I Rewrote Pokemon Yellow Entirely in TypeScript — Here's How It Runs in Your Browser

I spent months rewriting Pokemon Yellow from scratch in TypeScript. Not an emulator — a complete reimplementation, ported instruction-by-instruction from Z80 assembly into HTML5 Canvas. Play it here (bring your own ROM) | Source code Why? Because I wanted to know if it was possible. The pret/pokeyellow community has fully reverse-engineered Pokemon Yellow into readable assembly. I thought: what if I could take that assembly and turn it into something that runs natively in the browser? The entire engine is ~280KB of TypeScript. Zero game assets are shipped — everything is extracted from your own ROM file directly in the browser. How the ROM Extraction Works This was the most interesting technical challenge. When you upload your ROM, the game: Validates it via SHA1 hash Runs 14 specialized extractors that parse the raw binary — Pokemon stats, move data, map layouts, dialogue text, trainer parties, audio sequences Decompresses Gen 1 sprites using the original compression algorithm (RLE +