GTA: Rio de Janeiro is a mod of Grand Theft Auto: San Andreas. 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). Some version of the mod also change the layout of the city for a new one resembling the Brazilian city.
This mod and it's variants were very popular in Brazil, where it was sold in parallel shops as a pirate game.