The devs speak up: proudest accomplishments in Oblivion! The quotes speak for themselves.
http://rpgvault.ign.com/articles/701/701931p1.html
"I am most proud of the Havok physics."
"I worked on all non-combat and non-pathfinding AI plus gameplay. I am most proud of when an NPC does something the designers do not expect because they decide to "think" for themselves. Drives designers crazy. "
"I think my greatest source of pride, in terms of my contribution to this game, were the times during the play-testing phase when I was able to find a really egregious bug that no one else had discovered yet."
"I'm very happy with how the lock picking turned out"
"I did odd jobs at first, and soon ended up taking over the distant level of detail system - that's the system that allows us to store and render a simplified version of the world out to incredible distances. So that's definitely what I'm most proud of"
"game balance is considered to be one of the trickiest things to do well. I succeeded beyond my hopes and expectations"
"I guess for me, my greatest personal achievement has to be the Dark Brotherhood quest line."
"The fact that we could actually pull off the Battle of Bruma, with close to 30 NPCs and creatures slugging it out in a completely unscripted real-time battle... I'm still amazed at that."
"Personally, I'm most proud of the conversation system in Oblivion. I really wanted the world to seem like it is populated by living, breathing people - like an MMO without the annoying people. Any time I hear a good conversation in the streets or in a tavern, I feel like we've gotten a little closer to that vision."
"I'd have to say that the thing that I'm the most proud of was actually one of my first assignments upon joining the team - refining the Radiant AI schedules for all of the NPCs in the world."
"My title means that I had a hand in many of the 200-plus dungeons scattered across Cyrodiil. Most of the ones I worked on are random romps without quests attached. This gave me a lot of freedom to create interest through atmosphere and gameplay. I'm proud of several of these"
"As proud as I am of my dungeon work, however, I think I'm most proud of the collaborative work I did with some of the designers to get the Highwaymen and especially the Orc Adventurers into the game. The ghost pirate cave also. I'm definitely pleased with my ghost pirate cave."
"I would have to say that the thing I am most proud of, while working on Oblivion, would be working together with Brendan Anthony to track down and solve a notorious scaling issue. Essentially, characters, both NPC and PC alike, would suddenly expand or grow to immense proportions."