GTA Multiverse: SA VC GTA III run simultaneously via real-time portals

The Multiverse in Code: How One Moder Merged Three GTA Worlds into a Single Reality

The world of Grand Theft Auto modding has always been a playground for digital tinkerers, but a new achievement has entered the realm of possibility. Created by modder Dryxio, this unprecedented project doesn’t just blend classic titles; it fuses three disparate worlds—GTA Vice City, GTA San Andreas, and GTA III—into one unified, living multiverse connected by real-time portals.

This isn’t merely a simple crossover. The mod allows players to experience the chaotic fun of all three games simultaneously. Imagine CJ from San Andreas finding a doorway leading directly into the neon streets of Vice City, only to then step through another portal and arrive in the gritty environment of GTA III. The resulting experience is cinematic chaos, where players can traverse between these worlds as if they were simply flipping a switch.

The true genius lies in the seamless execution of this impossible feat. These portals aren’t mere graphical tricks; they are genuine windows into another game’s reality. As demonstrated in video showcases, characters can literally move from one game to the next, interacting with the physics and environments of all three worlds simultaneously. This level of cross-game interaction pushes the boundaries of what modding is capable of.

So, how is this digital magic achieved? The underlying mechanism is a staggering feat of technical reverse engineering. Dryxio managed to create a single entity where all three games run in parallel within one process, sharing a single Direct3D device. Each portal functions as a live GPU texture, eliminating the need for video capture or loading screens to fake the transitions.

When a player steps through a portal, the engine instantly swaps to the new game’s environment while the others continue running in the background. This real-time engine switching is what grants the illusion of instant travel, ensuring that every element—from AI and physics to saves and missions—retains full native functionality within its respective world.

The complexity behind this integration required deep-level manipulation of game source code. Dryxio accomplished this by decompiling the original source code for GTA III and Vice City, using community projects like re3 and reVC to create clean C++ code. To unify these systems, an open-source reimplementation of the proprietary RenderWare engine, called librw, was deployed to compile all three disparate game engines into a single, cohesive process.

This mod represents one of the most technically ambitious projects ever undertaken in the GTA community. It is a testament not only to human ingenuity but also to the power of combining advanced programming techniques to create something truly novel. While the project remains locked away for now, it stands as an undeniable proof that the limits of digital creativity are constantly being redefined.