Everything Disney has done with it since Legacy has been a waste of the license. It really says something when the best Tron game wasn't even official and was made years ago
I'll be honest, my favorite LAN games were always the simple, non-resource intensive, fun multiplayer games like Worms, Armagetron, or Liero. Allegiance is also pretty amazing at a LAN, if you can get 20-40 people who have a basic idea of how to play.
MomotypeMomotype
Others already mentioned good stuff. Good to know that Pretty much all oldschool consols such as PS1, PS2, PSP, SEGA Genesis, Nintendo DS, have emulators for Linux. So have fun with these.
I just looked this up and am playing it for the first time, it's alot like the free game you could download, basically the exact same as this but with 3D models, called "Armagetron".
Super addicting, neat to see a flash version!
Armagetron is a 3D Tron clone. If you don't know what tron is, think snake with an infinitely growing body, and instead of collecting Apple's, you have to avoid (your own and) other "snakes" while trying to get them to run into your "body".
I've spend countless hours playing this game. It's simple and makes you think. The only potential downside (or perk) is that it's an online multiplayer game (although I believe you can play offline against AIs, it's been a while haha). Best part is that it's free and available for Linux, Windows, and Mac OS X.
I haven't played this game in a long time, so I might be wrong on a couple of things about it, but check out armagetron. It's free.
I first played this at a summer camp in ~2007 (so on older computers than what you have), but it looks like it's still being supported. It's a competitive multiplayer snake- from what I remember you basically have to trap your opponents so they crash into your tail. There are several modes, including a team v. team mode. We played it over LAN pretty constantly, and I remember it being a lot of fun (and I'm not normally a multiplayer person at all, nor was I then). We were 12-17, but there's no reason why kids a couple of years younger couldn't play too.
I don't know if it's still alive, but back in the day I was quite fond of Armagetron Advanced.
Pretty sure it's an open source, 3d version of what you're looking for, although I don't know if it still has a community.