Valve Hands the Team Fortress 2 Source Code to Modders

“Unlike the Steam Workshop or local content mods, this SDK gives mod makers the ability to change, extend or rewrite TF2, making anything from small tweaks to complete conversions possible,” Valve explained.

Valve released Team Fortress 2’s full game code to modders. Every mod must be free. Valve’s own TF2 servers have spent years overrun by bots. The community now has the code.