I'll just make you a bit more popular, so...
Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks! Neobeo rocks!

As I said, we probably won't have to do complex trajectory calculation for every weapon, but only for few weapons - those that don't follow a straight line to be precise. Most weapon trajectories can easily be described by a straight line - single struct/vector (has a direction, projectile speed, damage and lifetime). Personally if the calculations are to be done in C++, I'd do them in OOP with class inheritance (sort of the way Unreal engine works).

I wonder if we can get coop working properly.