1. Abandonware
  2. Artificial Life
  3. Wargames

You probably already have a bunch of game sites that you check every week (or every day), so I won't innundate you with more. Instead, I'll point out my favorite lesser-known sites.

1. Abandonware

Abandonware sites let you download software which has gone out of print. The legality of these downloads is questionable. Some publishers regard abandonware acts as free advertising and permit it (or at least look the other way); others regard is as piracy and fight it. If you're on the prowl for abandonware, make sure you stick to the reputable sites and don't get lured into piracy/warez rings. Piracy sucks, but abandonware seems like it helps the publishers and game makers more than it hurts them. That's my take on it, at least.

Home of the Underdogs
Awesome site, the only one I check every week (even though 2005 has only seen two updates so far). It combines abandonware, freeware, and little-known commercial ware, providing links to games that you can buy, downloads for games you can't. Most of my favorite games of all time are available via The Underdogs. A must-see!

2. Artificial Life

This might put some of y'all to sleep, but geeky/academic readers might be interested. The idea is that it's possible to simulate systems of "life" on a computer. By "life" I mean the processes of birth, growth, reproduction, and death. At least, that's my definition. I'm certainly no expert on the subject! By the way, these aren't really "games", unless you create challeges for yourself (stable structures, etc.). I'll try to focus on the more interactive "eye-candy" than the pure math sites.

Artificial Life Links - Alcyone Systems
Yeah, I know, I'm giving you a link to a list of links. How lazy! It's a good page, though, and will probably be updated far more frequently than anything I put together! Oops, never mind! Bad links abound on that page. And it's only a few months out of date! A shame; looks like alife's popularity is in a bit of a slump. Oh well.
Ariel Dolan's Playground
Ariel created a bunch of Java applets which demonstrate flocking behavior and cellular automata.
Lotus Artificial Life
More Java applets, this time focusing mostly on reproduction.

3. Wargames

Ever since I was a kid I liked wargames. I didn't have anyone to play with, so I'd play both sides. Once wargames started appearing on computers, I quickly got hooked. Yawn, huh? Anyway, I'm sure y'all have similar stories. I'm also sure y'all are perfectly capable of googling "wargame", so I don't know why I created this section. Oh well, I'll try to keep it short.
Feels like an online magazine. Discusses both computer and board games. Has a discussion forum.
Focuses mostly on board games. Tons of info. Happy wading!
Home of the Underdogs - War
Great section, lets you sort by ratings, downloads, year, etc. This will let you download such computer wargame classics as: Panzer General, The Perfect General, Empire Deluxe, Age of Rifles, Close Combat, and tons of more. The amount of wargaming wealth at this site is insane!
Steel Panthers World at War
A free wargame! And it's huge! I really enjoyed playing Steel Panthers back in 1995 or so. Ten years later and it's still being updated! The tutorials teach you a lot about combat principles like supression, combined arms, and other stuff that I forgot. Okay, so it's not the best teaching mechanism (or I'm not the best pupil), but it's still fun (and free)!