1. Elder Scrolls V: Skyrim
First time I played Oblivion I hated it. A friend of mine gave me some good advice by telling me to mostly ignore the main quest and do what I want to do. Following his advice made me fall in love with oblivion. Some cool mods helped as well. That advice holds true to today. Skyrim's campaign isn't the best. The combat is rather mediocre. What sets this game apart is the scale of it. Exploring the world, joining guilds, doing side quests. That is what made the game great.
2. Halo 3
My first experience with online shooters was Halo 2. So understandbly I was very hyped for Halo 3. Considering it is one of two games I've probably spent over 1000 hours playing, it exceeded my high expectations.
3. Diablo 3
Huge dissappointment. For the first few weeks I couldn't even stay connected reliably. Everyone who I played it with quickly grew tired of it.
4. God of War III
A very good game, but somewhat disappointing. The trailers for this game is what made me buy a playstation 3. The quicktime events, and average combat ruined it for me. Then again I was spoiled by bayonetta shortly prior to playing this. Had I not, I would have probably overlooked most of GoW's shortcomings.
I love messing around with level editors. And that aspect of the game was awsome. This game also heavily influenced me into buying a playstation 3. Sadly the actual platforming in this game was a complete mess. Very dissappointing.