I think 2fort and turbine have already been made.
2Fort I have seen, I have also seen a Trainyard CTF (it was hosted by Telazack, please tell me if you remember him! I haven't been able to track him down)...but I haven't seen Turbine...remember who made it?
In any case, I was thinking of building either Gorge or Stage 1 of Pipeline (payload race). The only problem with Pipeline is that the gamemode_payload is designed for just that, I need a payload
race mod where the color of the spawn of the payload determines the team that it is on. You cannot have 2 different payloads for 2 different teams in the existing gamemode.