Majora's Mask
Reasons why
This was my first game for my n64. Didn't have as many temples as the others but since it was my first I didn't notice it until later. The game was really diverse and deep overall.
OoT
Reason why.
One of my earliest Zelda games aswell. The feeling at the time was awesome. Really felt like a Grand adventure. Dont know if this or Majora is my favorite Zelda.
Team Fortress 2
Really funny game, and very fun multiplayer. Probably my favorite multiplayer shooter.
Half Life 2.
Reasons why.
The story was really enjoyable and the level variety and atmosphere was great. First Played on 360.
Pokemon Silver
Was one of my favorite games in my youth. Spent so much time on it.
SSBB
Easily my favorite fighting game ever.
Fallout 3.
There is so much to do and so many places to explore this game is perfect to me. Little glitchy and all but I still love it.
Sonic 2.
Reason why
It was my first game ever. Personally I think it's the best of the four classic sonic games.
My overall favorite series
God Of War. All 3 of them
Reasons why
I just cannot help feeling like the biggest badass of all time while playing it. The games do a really good job of immersing me. Apart from that I like the gameplay being challenging enough while not overly complicated, the setting is cool, the main character makes the overall feel and atmosphere really believable and has really cool music and art direction.
Honorable mentions go to Ninja Gaiden and LittleBIGPlanet. LBP2 may replace sonic 2.