Wow ... I don't think their is enough room to list all of them.
However, the hands down the most disappointing game ever ...
X-rebirth Metacriitic score of 33 / 3.2 and to tell the truth that is BS, the Devs have thrown in A few hundred 10s too bump this score.
http://www.metacritic.com/game/pc/x-rebirth
I am now 35, When I was 19 I worked at electronics boutique (eb games or gamestop now for you youngns) This game came out and I was blown away. The followed up with newer verson and always out did their selves. They were never Big money maker games, however their core group of ppl loved them. The games always had A stigma of being hard ... they were not , just had to take the time to learn.
I would say I have well over 500 hours in X2 and Probably 2000+ between X3/X3Ap. When they announced rebirth, I was so happy. However as more came out about it ... I became very sad, I could tell from the info coming out , it was going to be watered down for the Masses, this was going be A game made for consoles .... threw all the new glossy graphics, I could see it was going to be epicley dumbed down so more people would buy it. It worked, the game sold well ... however it was so freaking bad. Its sad cause I knew the game was going too be bad, and it was worst then anyone could imagined.
This game was so bad, feel steam should of gave refunds .... Shame on them. Trust me it was bad.
Runner up would be BRINK !
Honorable Mentions
Watchdogs, Thief, D3, Dungons, Gotham City Impostors, Alines Vs Predators, C&C 4, BF4.
And A note to bethsaida, As much As I do love all your games ... Been playing since Dagger Fall. Stop hurting PC games because crappy consoles cant take it. You removed flight from Elder Scrolls games because consoles could not run them as well ... dont dumb your games down becuase of this.
Some of your best dungons were ones that were air mazes ... bring them back !