In mid-2000, Valve announced that "Team Fortress 2" had been delayed for a second time. They stated that they delayed "Team Fortress 2" because they were going to make Team Fortress 2 run on an engine they own, the Source engine. After their official announcement of the delay of "Team Fortress 2", Valve stopped releasing information about the game. Later, the game entered six years of silent development. Walker and Cook worked on various other Valve projects; Walker was project lead on "" and Cook became a Steam developer. 