I go to Edgewater High and something we all find fun is Minecraft. I'm assuming you want something where you can open a LAN server and quickly pick up and play games. Counterstrike 1 is good, Tribes 1 (if you can find it), Halo Custom Edition, and maybe if you can find it the cracked LAN version of Torchlight 2. Glad I could help!
Sources: I was looking for the same thing for a while.