Sometime in a previous incarnation of this site, I wrote about the fantastic indie game Darwinia and the less indie but still wonderful Galactic Civilizations 2. It's been a while, and I've found a number of gems since then, many of which were nominees or winners for Independent Games Festival awards (a virtual treasure trove of cool indie games). Here's a quick rundown:

• Europa Universalis III: Some game publishers think the best way to ward off piracy is to use cumbersome online copy protection schemes that serve only to annoy legit owners licensees. Other publishers eschew all that and create a game with such complex mechanics that players would be crippled without a dense reference manual, making it far more convenient to just buy the damned thing. EU3 falls in the latter category. With one of the steepest learning curves I've ever seen in a computer game, this is certainly not for everyone. The pacing of the game tends toward long slow growth periods punctuated by short bursts of intense tactical maneuvering. I read someone compare the excitement level of EU3 to that of fishing, which is a rather apt comparison I think.
• Armadillo Run: This is a really neat physics-based puzzle game. The goal is simple: build a structure, under budget, to move the ball (actually a rolled-up armadillo) to the designated blue target zone (some sort of interdimensional transport bubble thing). Various materials, each with their own physical properties, are available to build all sorts of Rube Goldberg type contraptions. There's a free demo with several levels playable, and the full version is $20. The full version also includes a level editor, and tons of user created levels are available to download, so gameplay is quite open ended. Also, check out YouTube for videos of some really crazy user created "spectator" levels (beware of horrible loud soundtracks, though).
• Grid Wars: This is a high intensity free Geometry Wars clone. Xbox360-less, I have never played Geometry Wars, but Grid Wars is apparently such a close replica that its developer was sent a C&D and instructed to remove the program from his website. Fortunately, others have taken on the task of keeping Grid Wars available. I'm not sure how well the keyboard/mouse controls work, but with a dual-analog game pad this game rocks! And it's free!
• Strange Attractors: And now for something completely different.. a game that uses only one button, ever. Push spacebar, release spacebar. Got it? This is really neat... You control a ball floating through space. When you push the spacebar, some sort of gravity generator in the ball is activated, attracting the ball to other floating objects. Using just this one function, your goal is to move the ball vertically through a series of increasingly dense and chaotic levels. As demented icing on the cake, you can use your gravity generator to sling hapless floating spacemen screaming to their splattering deaths. Also, it's free!
• Tranquility: A beautiful example of less is more in game design, Tranquility can be a very relaxing experience, requiring only the most subtle of mouse movements. I've seen it described as a flight sim, but it's really more of a float sim. There is no lift force, so it's not true flight. Instead, you have to bounce off of platforms to gain altitude and then slowly drift back down to the floor. Somewhere in this 3D space is a spinning target. Collide with the target and proceed to the next level. Simple enough. There's a free demo available with a different level daily, but the full version only costs $6.
• Pogo Sticker: By the developer who created the wonderful Stair Dismount (and then Truck Dismount), years ago. In this side scroller, you control a guy on a pogo stick using just the mouse. Move the mouse left and right to control direction, and click once or more to increase the jump height. But make sure you keep bouncing continually and don't hit your head too hard on the ceiling, or it's game over. The gameplay is simple but often horribly frustrating. There's not a whole lot of replay value, but hey, it's free!

I'm still going through the past several years' worth of IGF award nominees and winners. There are several demos I want to try out, and I'll post any that actually convince me to part with my $$$.