Although I play a lot of first person shooters, I'm more of a fan of MMORPG games and hack and slashes and whatnot. I can play games like Neverwinter, Diablo 2, and Silkroad for days. I love in-game economies and leveling up and even after you reach the level cap, there is so much to do, and you can improve forever. I will never play Diablo 3 due to the fact they removed the ability to item trade for PC players, so really, there is no reason for me to play it, when there are games like Path of Exile, Torchlight 2, and Grim Dawn, cheap (or free).
As far as in-game achievements go, for first person shooters and whatnot, I try to get them all, I'll go out of my way to do it, just something to hold my attention otherwise I wouldn't play much and would play something more fun. Although I can play DOD:S for quite awhile, most I can't play long.