Team Comtress 2 is a fork of an older version of Team Fortress 2, with a community development team fixing bugs, improving performance, and adding quality of life features, with the goal of having those changes pulled upstream by Valve to the modern game.
Seeing as how they are basing their work on a leaked (stolen) version of the TF2 source code from Valve, I don't see this project even existing for very long, much less contributing anything back to Valve.
This project seems pretty promising. How many players are online?
I’d love to see a TF3 some day, although I don’t know video games economics well enough to understand if it would make financial sense for Valve.
Funny side story - just before COVID, my spouse and I had a dinner reservation at the Fogo De Ciao here in Bellevue, WA. We came out of the restaurant after dinner to go up stairs and walk to the Cinemark to catch a movie. Behold - Gabe Newell was coming down the the escalator as we were going up. He seemed like a pretty down to Earth, chill guy. Afterwards I figured out that Valve has offices in one of the upper floors in the same building as the restaurant (Lincoln Square).
That is pretty interesting. I used to love developing with the Source Engine, and I found their code base to be stable and easy to read. I hope TC2 gets the long term support and care that it needs to grow a healthy community.
I worked on extending the Source Engine with C#, some 7 years ago, and I feel like I got pretty far, but nothing really usable: https://github.com/SharpMod/SharpMod
But I have not kept up with the changes of what exactly Source 2 is, how backward compatible it is, and how it compares with Unreal/Unity.
Has Valve ever made a statement on this? Sounds like a terrible idea to me / this could be taken down on a whim by Valve.