A technical project shared by modder Dryxio has demonstrated a way to link three classic Grand Theft Auto titles—Grand Theft Auto III, Vice City, and San Andreas—into a single, interconnected experience on PC. The modification allows players to travel between the three games in real-time using interactive portals.
Technical Functionality
In a demonstration video, the modder displays a character standing on Grove Street in San Andreas, surrounded by portals leading to various locations in Grand Theft Auto III and Vice City. These portals are not pre-rendered videos or captured windows; they are fully interactive, allowing players to fire weapons through them at NPCs located in the other game worlds.
According to the developer, the technical foundation of this project involves all three games running inside the same process while sharing a single Direct3D device. When a player walks through a portal, the game engine currently in control swaps seamlessly, while the other instances continue to run in the background.
Current Status and Availability
While the project has been showcased as a functional technical marvel, the modification is not currently available for public download. Dryxio has previously released other projects for the series, including a map editor for San Andreas and an aesthetic filter that mimics the 2004 PlayStation 2 release, but this multiverse project remains in development.
For PC players interested in the project's progress, the creator has suggested following his updates via his official channels for news on future availability.

