Condition Zero started development in 2000 by Rogue
Entertainment, and was initially announced in May 2001 at E3 of
that year. Rogue's producer for the game, Jim Molinet, later
that year moved to Sony and the development company went
defunct, leaving Valve empty. Later, they gave it to Gearbox
Software, the developers of the Half-Life expansion packs, so
that Valve could focus on the development rival Team Fortress 2
and its new engine.