Valve have just updated the Source 1 SDK on GitHub to the latest code based on Team Fortress 2, effectively making TF2 code source available.
SDK was previously updated in 2014.
Also this is just source code, not the assets (at least as far as I understand it).
Could probably just require the official game to be installed too and load the assets from that directory, or might even be able to use the shared folder, but not sure if tf2 uses that, i remember l4d and css and hl2 used to.
Could probably just require the official game to be installed too and load the assets from that directory, or might even be able to use the shared folder, but not sure if tf2 uses that, i remember l4d and css and hl2 used to.