so i was playing ut99 when i came across a an awesome mod thats called monster mayhem. the objective of the mod is to is wipe out thousands of monsters with some new and old weapons(hitman rifle,unreal minigun,unreal amsdrifles) what makes this game mode awesome is that you get to play with 6+ other people. basically its serious sam mixed with nazi zombies just with more weapons and more enemies(that are hard) its loads of fun;
 
here's there website: http://unreal-mayhem.com/nuke/index.php