It is the only multiplayer game to appear in the collection. The game is a sequel to the original Quake modification, Team Fortress, and Valve’s Half-Life modification, Team Fortress Classic. Team Fortress 2 is a multiplayer team-based first-person shooter that was first available as part of The Orange Box. All Orange Box games use hl2.exe as the executable name, probably because they shared engines (unlike forking it like for CSGO) to allow them to run on consoles easier and download faster on PC. Technically, at its core it is Half Life 2. It’s because that is the engine that tf2 runs on.
