Good Multiplayer FPS

I'm in search of a good multiplayer FPS here is what I am looking for:

-About 16 max players

-No gigantic BF2-sized maps 

-Not too slow paced

-Lots of different game types

-Team-Based with some solo if possible

-Any system requirements

-Requires some skill (No spray ftw)
 

Any recommendations?  Thank you ahead of time to all who reply in a helpful way.

Good call on FEAR combat. Guys, it's FREE!Shrodinger

Sniper Elite.  It is either team based or "every man for themself."  You could either run-n-gun or find a good spot and snipe, snipe, snipe. 

Unreal Tournament 2004

Call of Duty 1 and 2