VDrift. Cross platform driving game with a neat physics engine and really playable AI and decent graphics. You’ll need a steering wheel to get the best out of it of course.
0AD is a Real Time Strategy (RTS) game with professional style graphics, and the kind of detail you would expect to find in a commercial product. Think Microsoft’s Age of Empires series and you’re close. Still in pre-release, but available if you’re happy downloading source code.
Hedgewars is a lovely looking little turn based game which feels a little like the classic Worms title of yesteryear. Splatting hedgehogs may seem unnecessarily cruel, but it can be cartoony fun too it seems.
FlightGear delivers a beautiful flight simulator to your computer, chock full of scenery, aircraft, locations, and lots of open formats for you to enjoy and edit. Glorious.
Sam & Max. Do old computer games age? Only you, a psychotic rabbit – and some great looking comic caper adventures – will be able to tell. Not open source, but still free. As in bird. Here birdy birdy.
Spring:1944 takes you back to the days when tanks were tanks and horses were for the milk round. A WW2 RTS game with great graphics, the usual challenges and a focus on managing resources across a large playground.
3D Ultimate Pinball is not a *real* free game, but it does have a free demo which gives you unlimited play on a proper pinball machine. The full version simply gives you 4 extra tables, is all. We like pinball. A lot. And this is fun.
OpenTTD is an open source remake of the classic Transport Tycoon game, and it does a grand job. OK, so if you’re not an RTS fan you’re going to sigh a little, but it’s definitely fun if you’ve got time and imagination to spare.
Powermanga. Sometimes you just want to shoot pretty coloured stuff up, in which case this 2D arcade game is for you. You get 41 levels and full joystick support. Whee!
Planeshift is a beautifully drawn online role playing adventure game (yes a mmorpg), which promises to remain totally free with none of that premium commercial stuff. Which makes it sort of unique. If spells are your thing.
Ultimate Stunts is apparently not just another racing game. For one thing, you can design your own tracks. With loops and jumps and all sorts of excitement. Fully open source, with cross-platform support for Linux and Windows.
Boppin may be garish purple but that’s the least of your problems as you struggle to complete the puzzles, release monsters and defeat your Hunnybunz enemies. Huh?
Dark Oberon is a free RTS game but with a difference. The graphics are created out of real plasticine models. Cute. Ultra slow development on the part of the sole developer, but still worth a look.
Pingus. Whoa, it’s Lemmings. With penguins. 22 tested levels and around another 100 + untested. Plus some new moves (like Jumper). If you haven’t played Lemmings, you’re in for a treat. But boy it’s hard.
Table Tennis Pro offers a very credible alternative to commercial ping pong games, with cool graphics, a nice control system and some tricky gameplay. As long as you’re prepared to learn. Nice.
FreeOrion. Space, the final frontier…ah sorry, wrong game. Anyway this is a turn based space empire game where you get to conquer the universe and beyond. This space stuff looks pretty complex from over here.
Warzone 2100 gives you the chance to rebuild the earth after a devastating nuclear holocaust. Good job it’s open source then. And with some nice graphics and a vibrant dev community, this RTS game looks good enough to trounce.
Freedroid. Kind of similar to above, but with robots. And penguins. Robot penguins. Slash, hack, spells. And penguins, darn it, penguins. What more could you possibly need?
Secret Maryo Chronicles is a cute 2D platform game which is vaguely familiar. Small chap, runs around grabbing power-ups, leaping over enemies and beating levels. Wonder where they got the idea from?
GNU Backgammon is not just a game, it’s also a teaching engine which’ll hone your BG skillz beyond your wildest dreams. Based on a neural network and smarter than you.
Command & Conquer Classic. THE RTS game of the age. Fast, furious and completely addictive. Now transferred from the commercial to freeware world as a marketing tactic.
[Part II here...what classically beautiful and massively successful - iconic even - game now lives again as an online freebie?]
[Part III here..]