A former Rockstar developer spoke about the canceled multiplayer for GTA 3
Former Rockstar Games technical director Obbe Vermeij confirmed in one of his posts that multiplayer could appear in Grand Theft Auto 3. The code for it was already ready, but the studio decided to abandon this idea.
Since multiplayer was already present in the first two GTAs, the developers decided to add it to the third part. According to Obbe Vermeij, they managed to write the code and prepare the basic gameplay, but then decided to abandon the mode due to too much work. Rockstar Games made another attempt with GTA Vice City, but this idea also ended in failure. Multiplayer had to be sacrificed during the development of San Andreas in order to meet the console release, so only co-op was left in the game.
Let us remind you that Obbe Vermeil recently spoke about the mechanics of police pursuit in GTA Vice City.