There are many different versions of the mod, by different people, but all of them try to change the aesthetics of the game (cars, ads, music and others) to new ones based on Rio de Janeiro, a Brazilian city known for being a tourism destination (and also for elevated crime rates).
This can result in very late detection of potential issues and no high level knowledge of `this road is blocked ` instead, the system only indicates that there's something in my way to be avoided. GTA: Rio de Janeiro is a mod of Grand Theft Auto: San Andreas. This is done every frame for each entity and no knowledge of the previous frame is used. This involves, each frame, checking the local environment for any potential obstructions (vehicles, pedestrians, objects), building up a view of that obstruction from the local vehicle (creating a `front facing` polygon which is a list of points/lines that the vehicle will need to avoid in order to not hit the obstruction), generating information about the road the vehicle is on so they can avoid going off-road into buildings and finally generating and detecting the best steering angle to avoid all the obstructions. This is explained in the patent, with it stating that, "As an additional drawback, conventional systems relied almost entirely on local traffic avoidance for NPCs to avoid collisions. The patent describes a new system that will allow NPCs to act intelligently and react to situations and hazards in real-time. Rockstars Games has applied to patent a new technology called "System and Method for Virtual Navigation in a Gaming Environment".