The computers we have access to are a little bit limited in that it's difficult to install new games on all computers. But - they do have Steam, which lets you install any game on Steam! So we play a lot of Steam games.
We have played a lot of TF2 a the LANs. Maybe a bit too much. We play a lot of different game modes, including the classics, and more custom ones like the PASS bass game and coop vs robots.
(Steam) Not everyone plays Minecraft, but those who do are typically very into it. We even have our own server! Come join us at beefyserver.serveminecraft.net. Some of our regulars include Thommo1993, l33tllama and blatu. It's been a bit quiet lately due to the LAN not being on, but you do get the odd visitor.
(Steam) This one is a big favourite with a lot of people. It's easy to get in to, hard to master. It can be quite funny sometimes when the golf ball ends up in unusual places. And funky physics. This isn't a free game, but the admins are quite likely to gift you a game if you'd really like it :)
(Steam) This is a vey easy and approachable game to play. Sometimes it's fun to play at the end of a LAN. Some of our gamers even make their own maps for everyone to play! It can also be very challenging competitive.
We only started playing this game more recently. But it is a lot of fun. It's a zombie shooter game with classes. Pretty good considering it's free.
Some other games we have played include