Invasion is an open-source restoration of Valve’s Team Fortress Invasion, using Source 2013. For those not familiar with Team Fortress Invasion, it’s essentially the third known iteration of Team Fortress 2 during its lengthy development and was partially leaked in 2003.

It’s better to imagine it as an entirely different game from the Team Fortress as you understand it. Levels were likely to be large and open, featuring vehicles, with various goals, fauna, resources and a number of dynamic obstacles that would manifest themselves while playing through a level. In a sense, it’s somewhat like an FPS/RTS game and would have been very innovative and ambitious for its time. Players would have been far more involved in both defence and resource management, and there would have been an emphasis on coordination between players during rounds.

This iteration sadly ceased being developed in 2003, likely because the team moved on to helping with getting Half-Life 2 finished, but because of this there’s a ton of legacy code (such as the game using physical models for impact effects) and the game was in a barely-working state (team spawning didn’t work, vehicles didn’t work and so on). Work on restoring the game is obviously no trivial task; the only assets that exist are two models and a few random files, everything else has to be produced from scratch using conceptual art as reference.

The aim of Invasion is to produce an easy way for people to see some of the functionality in action that was intended for this iteration of Team Fortress 2. If we manage to produce something playable, that’s a huge plus but is currently a far far away goal.

Who’s responsible for this?

So far, most of this has been developed by myself, hogsy. Additional models for some of the buildables and other resources were provided by Eukos, and the player models were decompiled and released by ScarT a while ago. I’m actively seeking other people interested in investing some time in this and willing to contribute, so if you’re interested, feel free to spam my email; markelswo@gmail.com. I’m desperately looking for people who can help produce models, even as placeholders, for the project.

Awesome! Where can I download it?

The project is currently still under development, but the entire thing is up on GitHub.