Today as part of the Source SDK update, Valve have released the entire source code of Team Fortress 2, both client and server side. This source code is released under a non-commercial license which enables you to create from a mod to an entire game using the source code.Details of the Team Fortress 2 source release from the Team Fortress blog:Mod makers, rejoice! Weve just released a massive update to theSource SDK, adding all the Team Fortress 2 client and server game code. This update will allow content creators to build completely new games based on TF2. Were also doing a big update to all our multiplayer back-catalogue Source engine titles (TF2, DoD:S, HL2:DM, CS:S, and HLDM:S), adding 64-bit binary support, a scalable HUD/UI, prediction fixes, and a lot of other improvements!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.The SDK is licensed to users on a non-commercial basis, meaning that any mod created using the SDK must be free, and any content in those mods must be free. TF2 mods may be published on the Steam Store, and after publication will appear as new games in the Steam game list.Players have a lot of investment in their TF2 inventories, and Steam Workshop contributors have created of a lot of that content. The majority of items in the game now are thanks to the hard work of the TF2 community. To respect that, were asking TF2 mod makers continue to respect that connection, and to not make mods that have the purpose of trying to profit off Workshop contributors efforts. Were hoping that many mods will continue to allow players access their TF2 inventory, if this makes sense for the mod.Key LinksTeam Fortress SDK Blog PostSDK Installation GuideSteam SDK Source Code on GitHubYou can learn more about the Team Fortress 2 source code release in the video below.