Portal 2 - I think Portal needs a sequel because it's Portal and who doesn't love Portal?
Left 4 Dead 2 - A great game that was a sequel to another great game. Why wouldn't we want a third in this amazing series?
Catching on Valve?
Duke Nukem Forever - I want a better Duke Nukem game that doesn't take 13 years to come out and still suck pretty bad.
Bulletstorm - Bullestorm was a great game with great everything. No need to be specific about such a great game. I would love a sequel but Epic Games executives said People Can Fly can put their time and money into bigger and better projects.