The Locusts were originally going to be called "Geist". Epic had a hard time shipping this, however, because Nintendo previously had a game using the same name.
Gears of War was originally going to be a game called 'Unreal Warfare'. It was going to be a large multiplayer game that was set within the Unreal universe and would be the next Unreal game after Epic's previous Unreal Tournament. However, the team decided to strike the game from the Unreal series because it travelled too far from the Unreal universe.