Quake3, if you liked the Quake games in multiplayer, this is a given. Everything the first ones had, but moreso. Will really show off a good system.
Cons: The CD Key anti-piracy system it uses bugs me, you have to ‘ask’ for permission to play. If there’s a problem with the key server, you’ve bought yourself a coaster until they fix it.
For driving games, ReVolt. It’s a fairly good driving sim, except with RC cars and wild and crazy tracks. The simulation is excellent, the tires all act independantly, so if you have oil under on tire, the car drives as if that wheel alone is oiled. If the car is only partly on the ground, it acts in a way that seems appropriate. As such, it doesn’t feel ‘wrong’ like some driving games do. And, best of all, it’s multiplayer. Up to eight (at least, maybe 12) players can play a few different types of games. The cars are VERY good, individual feel and great personality (the two secret cars need to be seen to be believed, a UFO (no wheels) and a Panda (yes, the ‘bear’) on wheels.
Cons: You have to play the game and win to open tracks, instead of just playing what you like. Some tracks are nearly impossible to win on. (Good skill range though.) (And you can unlock tracks with the cheat code, if desired.)
Age of Empires II is a pretty good game. Similar concept to the first. It’s got ten or fifteen cultures, all with special abilities and discounts on technology. The cultures are nowhere near as different as the Starcraft races, but they do have a different feeling. (Britons get elite longbow troops, Vikings get ships, etc. Each culture has one distinct unit and discounts or off-limits areas to further distinguish them.) It has many handy features, like being able to auto-find idle workers, so they don’t stand around after finishing a job. Also, they can hide in buildings during attacks, not only for safety, but also to give those buildings an attack (one arrow per peasant… not much, but useful.)
Cons: AI… RTS games have never had a good AI and AoE2 doesn’t distinguish itself in either direction.
I’ll second the suggestion of Sim City 3k… It’s not too much different from the idea of the previous ones but it is stable (unlike 2k) and doesn’t have horrendous ‘issues’ (again like 2k). It’s what Sim City 2k should have been. A fun game, and addictive.
Ultima Online… I don’t like this sort of game, but friends of mine love it. Prepare for a time sucker though. Also Everquest and Asherton’s Call are very similar.
Cons: Buggy, laggy, expensive (monthly fees), and filled with cheaters/lamers.
Unreal Tournament is similar to Q3, but without the key server nonsense. Cheaper too. Not quite as pretty, and the levels don’t feel quite as smooth. Better bots though, more fun if you don’t have great net access.
That’s about all I’ve played in the last while.
Sports sims bore me (well, sports bore me) and most driving games are often crappy (same few tracks, with no variation (all scenery is flat, the track is essentially featureless)) counting on a license (Daytona, etc) to sell the game. RTS games are good, if you get Starcraft, AoE2, Total Annihilation, or another good one, otherwise they’ll be buggy and unbalanced. Strategy games… well, if you like chess, get Chess Master (whatever number it’s at now) etc. Shootemups… Q3 and UT dominate this area, with Half Life: Team Fortress Classic and Tribes pulling ahead if you like team games.
Hope that helps.