- 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.
- Team Fortress 2 is nearing its 20th anniversary, with the class-based first-person shooter first released in 2007.-
Sourcecode’s repo: https://github.com/ValveSoftware/source-sdk-2013