An experimental mod connects GTA III, Vice City, and San Andreas into a single interactive world using real-time portals and simultaneous game execution.
A Modder named Dryxio created an experimental mod that allows players to connect all three games Grand Theft Auto III, Grand Theft Auto: Vice City, and Grand Theft Auto: San Andreas in one common area. Players do not need to load another game. Instead they can move through portals that allow players to switch between those three games while all of them run at the same time.
The portals themselves act as interactive windows, rather than pre-programmed transitions. It is possible for the player to see what is going on in another game world, fire weapons through the portals and instantly become the protagonist of this game. Non-player characters, cars, physics and AI work independently in each game, allowing interaction across the three game worlds.
This is possible because the three games run in one process and use one Direct3D device. Each portal shows a real-time rendered view of another game through the GPU and the transition between games simply transfers control between the game engines while the rest of the games run in the background.
The system was created by modifying the open source re3 and reVC engines, using plugin-sdk to connect to the San Andreas game, and by replacing the native RenderWare engine with the open-source librw engine. Such a setup allows the three games to operate simultaneously while maintaining their separate missions, saved games, settings, and gameplay mechanics.
While the modification is not yet available to the public, it is a demonstration of what community-created tools and reverse-engineered game engines can achieve, surpassing the capabilities of the original game software. It showcases the possibilities of open-source game development in extending classic games with features not originally considered possible.
