Excessive Unreal 2 is one of the most chaotic, stupid, hilarious, and insane mods ever made for Unreal Tournament, and it has incredibly well-balanced, action-packed gameplay. Demo 3 consists of 15 playable maps, all of which have been thoroughly tested and refined for a long time now. If you like Serious Sam, Doom, and Unreal - especially when blended together in the most absurd (yet somehow perfect) way - this mod is for you.
This is the hilarious and awesome Monsterspawn mod by Asgard which allows you to spawn ANY monsters you want in multipleyer games (or singleplayer, actually...
This is the full package for EXU2: Batshit Insane - Demo 3, version 4. It includes all the necessary files to get things going.