The definitive list for the best LAN games of all time.

[Eclectic Dreck]

If age and platform are ignored:

Starcraft
Command and Conquer (I'm partial to Red Alert 1 & 2, Tiberian Sun myself)
Quake 3
Unreal Tournament
Counter Strike
Ghost Recon
Action Half-Life

 

[Flying-Emu]

Starcraft. I vote it to be number one.

This and Unreal Tournament, and we have a /thread.

 

[Bajaraja]

Starcraft, Warcraft (DoTA)
Command and Conquer
Quake
Unreal Tournament
Anything made by Valve

 

[Fenring]

C&C is good. If people like it, maybe a squad based RTS like CoH or DoW2. And this may sound a little crazy, but Civilization IV LAN can be pretty fun.

 

[SonicKoala]

All my choices have been said already - but yeah, Warcraft 3 (particularly DoTA, or HoN is good too), and Counterstrike: Source.

 

[Maeshone]

If you don't care about graphics too much, then Aliens vs Predator 2 is a fun choice. 3 different playstyles in one game, and we play it on every single one of our lans.

 

[Christemo]

Killing Floor. it takes barely any space and has very low requirements, via Steam you can just click your friend in killing floor and click "join game" and then your ready for some ZED killing.

 

[Selka]

I'm giving another vote to StarCraft, you can with up to 8 people and there are some great 4v4 team maps out there. Rise of Nations is often overlooked, but I had a lot of fun with it. If you're looking for something outside the RTS and FPS genres, and want to be able to play more than 4 people (sorry, Borderlands) I would suggest Diablo 2 if you've never played it before. It has aged surprisingly well.

Guild Wars, Game of the Year is only $20 on Steam. I found it more rewarding immediately than WoW, and if you're looking for more co-op play than versus, this is a good bet.

Team Fortress 2 is also only $20, possibly the best $20 I've ever spent on a game.

 

[Sapphire_Blue]

Dungeon Siege is a pretty good RPG with LAN.

Also, StarCraft.