okay Bethesda made the game and Obsidian wrote the plot and changed to creatures , they should count themselves lucky they were given a another chance to fiddle with a game again . its a Bethesda game bottom line . oblivion with guns . or did Obsidian do that one too ?
Obsidian developed Fallout: New Vegas (that means they wrote the story, created the world, created the weapons, the monsters, the quests...) and all of its DLC.
Bethesda developed Fallout 3 and its DLC.