Valve has opened up Team Fortress 2's full client and source code, encouraging players to 'change, extend, or rewrite' the game in any way they like. However, all mods must be released for free.

Later this year, the Team Fortress 2 Classic mod will arrive on Steam to let you step back in time to the early days of Valve’s class-based shooter, when it was more game than hat collection ...

Valve has officially released the full client and server code for its seminal first-person shooter Team Fortress 2 online. Fans of the game are encouraged to “change, extend or rewrite” Team Fortress ...

Why it matters: Team Fortress 2 launched 17 years ago but still receives significant updates, and its player base is as healthy as ever. The latest patch fully unlocks the game's SDK, releasing ...