The Elder Scrolls IV: Oblivion Oscuro's Oblivion Overhaul v1.2 Mod
 

This mod changes the game so that monsters and quests have a set level instead of scaling based on the player's level. The latest version includes even more changes to the monster and character levels, making the game more difficult and more realistic.

http://www.gamespot.com/pc/rpg/theel..._&subj=6147372