Alien Swarm can be fun at a small LAN. It's a top down shooter that came out in 2010 and is free on Steam. It never got much official support beyond the base campaign, but there are a handful of player made maps worth checking out.
If you just want to have fun, start a game on low difficulty and anyone can keep up. On the highest difficulty level though, shit gets intense and you'll get a buzz from beating it. Friendly fire and line of sight will have you yelling at the wanker using a flame thrower at the back of the pack. It's even better at a LAN because at least you can smack him in the head.
I found it a nice break away from FPS and if you've never played it, it's worth a shot.