Well, I been playing a free Half Life 2 total conversion called
NeoTokyo and I am loving it. It requires that you have steam and Half Life 2 ( doesnt have to be installed) and an internet connection in order to play. Its a squad based tactical FPS set in a tribute to Ghost in the Shell. I hate anime but setting aside its amazingly solid and lots of fun.
It plays sort of like counter strike so much as one death kills per round and heavily tactical in execution. It has a class based system (assault (medium), recon (light), and support (heavy)) and each have varying strengths and weaknesses. The game is heavily centered around vision and thermoptic camouflage as seen in Splinter Cell Chaos Theory. That you become invisible to your background except for a slight silhouette shimmer effect.
In fact, I am just going to stop there. You know if you like tactical shooters so if you do and want a new fresh coat of paint that is fun. take a small moment and check out the link above it will tell you everything you need to know without TL

R.
Want a good server to play on or invite me to one? Add me via steam: Killijin.