Duke Nukem 3D was the first game I remember playing (When I was 6) and it was an awesome game.
I got Duke Nukem Forever and it sucked.
Also Valve needs to announce Half-Life 3,Half-Life: Episode 3, Portal 3, Left 4 Dead 3 and Team Fortress 3 at the next E3. If Valve does this I will go up to their headquarters and throw my wallet threw one of their windows.
Team Fortress 3 is quite doubtful considering the amount of updates that are being released on TF2. Plus, TF2 is as good of a FTP as you will find, making TF3 a better game that would be free...I would say that's impossible. TF2 has made such good progress and a lot of people still play it. The only time I can see Valve making a new TF game would be if TF2 really got a massive decrease in activity.