What are your top 10 favorite single-player first-person shooters?

[Funtime]

I mostly prefer FPS for the multiplayer, so naming 10 single player campaigns that I loved is kinda tough. I can do 5 though.

1. Turok (surprised this hasn't gotten any love so far. Was awesome for it's time)
2. Goldeneye
3. Halo 3: ODST
4. Halo Combat Evolved
5. Half Life 2