Aliens vs Predator 2
HQP - High Resolution Textures
"High Quality Pack 2.0 - High Resolution Textures" is the bigest mod I ever made. As you can see on the screenshots, mod adds about 500 high resolution textures to the multiplayer part of the game.
Well, singleplayer is affected too but not as much as MP. I was making this mod more than a year, and its almost 10 times bigger than previous version. Its not perfect however. Textures I made at the begining are not so nice as the latest ones, and stuff like that. But it still looks better than original ones, I hope :)