The community project started in 2019 and was about 60% done. Selim, who couldn't type an HTML line, used AI agents like Codex and built a pipeline where agents find the next function, reverse it and review it against the assembler code. From when he started, the complete reverse took two months.

Selim compares the game's binary file to a cake and reverse engineering to finding its recipe. Using disassemblers you analyse and map the binary, then rewrite it so that, when compiled, it gets as close as possible to the original. With that source you can modify anything, including the physics engine.

An agent finds the next function to reverse in a logical order, fetches its assembler code and pseudocode from Ghidra, and passes it to another agent that rewrites it. A review agent compares the rewrite line by line to the assembler, the source of truth, until they reach consensus, then a human tests it in game.

Each reversed function is packaged as a plugin or mod: the game's original function is unplugged and the reversed one is plugged in, so functions can be tested one by one or in batches. Selim let agents run for hours, sometimes reversing 200 functions in a night, then tested in game.

Technically the code is your own since no line is copied, but everyone who reversed a GTA had to remove their repo. The GTA 3 and Vice City team faced a complaint and potential millions in fines from Tech2, and settled by agreeing never to touch Rockstar products. Nintendo is more lenient.

Super Mario 64 launched the movement, reversed in about four years, allowing native ports to PC, Mac, Linux and Nintendo 3DS. Pokémon Red, Blue, Emerald and Crystal followed, letting the community create games like Pokemon Unbound. San Andreas has between 12,000 and 15,000 functions.

The code contained an almost finished multi-protagonist system, the mechanic later used in GTA V with Franklin, Trevor and Michael, letting you switch characters in free mode; a recent mod reactivates it with a button. Missions were written in GTA 3 Script, Rockstar's own BASIC-derived language.

In the mode, CJ goes to his house, sits in front of the TV and launches a console to play Vice City or GTA 3. Because all three games are now reversed and share an engine, GTA 3 runs inside San Andreas with frames shown on the TV, saves included, without lag.

A former Rockstar developer from 2002-2003 told Selim that the textures are photos taken in real life, from a two or three week trip between Los Angeles and Las Vegas. Selim tracked down locations, recognising doors and cracks, and even found a shop from the game.

Selim built a tool where you upload a video of dancing or walking, such as MrBeast dancing, and it detects the skeleton and outputs a game-ready San Andreas animation in about five seconds. It also works with motion capture from two phones and is part of a 35-tool modding site.