Yeah the FPS "Unreal Tournament 2004" had 100's of mods, there was even a 100 thousand dollar Mod contest. One of the best ones for UT2004 was "Alien Swarm", - you choose your soldiers medics, heavy gunner, grunt, etc then head out and kill aliens simular to the movie Aliens on planets or abandon warehouses. You had to seal doors or unseal them while your team were fighting of the hordes of aliens coming at ya, install gun turrents to help ya out, really cool mod yet all it was, was just a top down view RTS gameplay still it gave that atmosphere of sheer terror when playing it
