From Team Fortress Wiki
"Team Fortress 2" is one of the song titles featured on the official Team Fortress 2 Soundtrack, listed as track number one, as well as being track two on The Orange Box Original Soundtrack. Known as the 'theme tune' of the game, it is the song featured in the Meet the Heavy short and Trailer 1, as well as being one of fifteen different main menu themes. A blues cover is also included in the soundtrack for Poker Night at the Inventory.
- One of the defining features of the Team Fortress 2 (Main Theme) is the prominent semitone at the end of every phrase in this song. The direction of this semitone is also the characterizing difference between the domination sound cue, and the revenge sound cue.