I know they aren't the most popular genre on the forums, but a few of us play FPSs old and new quite often - and play them primarily for the single player campaign. So, what single player campaign are you playing through?
As for me...
In anticipation of Killzone 3 later this month, I am currently replaying the campaign for Killzone 1 and Killzone 2 (previously I got "stuck" in one, but loved playing through two). I think that these are some of the best looking games from each respective gen, though KZ1's gameplay is lacking in many ways. KZ2 is ace. Anyway, I have a few other games in the genre I hope to get to soon...some I have shamefully never played!
How about you? What are you fragging?