PainKiller? - Perhaps one of the best games I ahve played in a long time. - First levels are a tad poor, but it gets better... Much better.
FEAR - Seems good for a lot of people, but the ending was a bit... Well... less said the better.
Deus Ex / DeusEX2 - Kind of ok I spose?
Hellgate London. Not bad actually but you have to get into it.
UnReal / UnReal 2 - Very nice, but you either love or hate it I find. I love it, but dont want to play it again for a while.
Quake 2 / Quake 4 / Doom 3 - Quake 2 is refreshing and infinitely playable. In my books, they make *** ultimately perfect game that simply has not been beaten even today, so if you have never played it before... Do it now. Quake 4 & Doom3 are just too close to call. Q4 is kind of like D3 but more humans are involved, and you dont need to rely on the torch, but other than that, there is far too much of one in the other, and I love Quake 2 and hated D3 so getting Q4 was kind of ruined for me.
COD4 - Yeah, I love COD 1+2 and only had COD4 for a couple of days and its sweet.
MOH:Airborne - Actually some dont seem to like this game, but for me, it was pretty cool and funnily enough, I cant stant MOH:AA but why?
Actually a kind of spenner in the works, try another old game - Freedom Fighters. Third Person, but its actually a fun game to play.