Valve adds "all the Team Fortress 2 client and server game code" to its Source mod tools, letting modders "build completely new games based on TF2" and publish the…

Valve has just issued a massive Source SDK update giving modders access to the Team Fortress 2 game code, opening the door ...
Engadget

Valve hands the Team Fortress 2 source code to modders

Valve is handing Team Fortress 2 modders the keys to the kingdom, as long as they don't try to make any money from it. The company has added the client and server game code to the Source software ...
PC Gamer

Pre-Fortress 2, a mod that bridges the gap between Team Fortress Classic and TF2, is coming to Steam with a whole lotta grenades

Team Fortress 2 modders love nothing more than imagining alternate histories for Valve's long-running multiplayer shooter, and this year has seen several of these nostalgia-tinged conversions migrate ...