I’ve looked at the code and it looks do-able. But, I thought it would be best to check with some experts. Is it possible to have 4 teams competing?
4 Teams?
I’m not an expert, but I see no reason why it shouldn’t. There would be quite some work involved to get this right though. Most of it shouldn’t be too difficult, just looking through the code where it expects two teams and where it checks for the player team, etc. Then you’d have to make some custom models or skins, change the UI, … And maybe a new gametype, because I can’t see objective working very well with more than two teams (who’d defend, who’d attack and if two teams had the same goal, why should they fight each other, in other words why would they have to be separate teams?). 
You couldn’t use any existing maps though, because they all have red team and blue team spawnpoints.
Is that OK not to be able to use any of the existing maps? I read the agreement and I wasn’t real clear on that point. I have two new game play modes where 3 or 4 teams of (up to) 8 players would add a lot to the fun.
Oh, it’s perfectly fine. I was just implying that if you make a mod supporting 4 teams, you will have to make your own maps to play it. That’s all.