FOnline Engine
From FOnline: 2238 Wiki
The FOnline Engine is an online game engine, meant to support Fallout and Fallout 2 graphics as well as the other games files (.dat, ...). The development of FOnline Engine started in early 2004, developed by a Russian team, and has never been connected to any Interplay or Bethesda project. FOnline stands for Fallout Online.
The engine allows players to play together in a fallout world, travelling across the same worldmap, meeting the same NPCs, fighting creatures together and achieving quests. Each player's progress is stored in its pip-boy (The quests progress for example), gain experience and levels based on his individual actions, and so on.