I play CS:S a hell of a lot. Games that run on the basic source engine (CS:S for example) will work on my computer, where as ones using a fancier version (such as tf2 or l4d) don't run so well (20fps at low res/low settings). Plus, there are so many different game types that you can play it over and over again. It is always good to go back to a bit of cs_office or de_dust2 every once in a while though. lol