Machinarium is a visually gorgeous, very slow-paced point and click adventure game, somewhat in the vein of old-school LucasArts games like Maniac Mansion or The Dig. You'll wander around alien-looking landscapes, solving puzzles, combining inventory items, and generally clicking on everything until you find the right combination of doodads and actions to let you proceed. Clicking the link above will take you directly to a demo - the whole game is done in Flash, so you can get a very good sense of how the game plays right there in your browser.
Your strange little robot must navigate a strange world full of other strange robots.
It sure is pretty, though.
You'll notice on the front page that Machinarium's price has been knocked down substantially, from $20 to only $5 for the next week, in what they're calling a "Pirate Amnesty Sale." According to their blog, the DRM-free Machinarium has been pirated by somewhere between 85 and 95 percent of the people who played it, and so they want to entice those people to come buy a legal copy with a deeply discounted price.
I'm not entirely sure how I feel about their stated numbers or their response, as I mention in the comments below the blog post. I played the demo for Machinarium when it first came out, and while I didn't buy it, I didn't then go pirate it either. I just didn't play it. It frankly didn't seem like something I wanted to pay $20 for - it was a visually remarkable game, but not all that much more so than Amanita's two previous games, Samorost and Samorost 2, which were entirely free and $5 respectively. It was also hampered by a rather cumbersome interface - you need to walk your character next to an object before you learn whether or not you can interact with it, for instance, and the walking speed is quite slow.
I have no idea how Amanita came up with the 85-95% piracy number for Machinarium (the blog calls it their "estimate from the feedback", which could mean almost anything), but I'm skeptical of it. I'm a little bit skeptical that there are that many people who want to play through a slow-paced point and click adventure game at all anymore, and I'm more skeptical that those who really do would choose to steal rather than pay for one of the very few ones that gets made these days. And given that my initial response to the game was, "It's very pretty and neat, but it's not worth $20 to me," I'm naturally inclined to blame their poor sales on overpricing their game rather than on too many people stealing it.
That said, I think $5 is a fine price ($10 also would have been reasonable) for a great-looking independently produced adventure game with a lot of charm, and Machinarium certainly is that. I wish the undertone of "obviously you pirated it before and now we're guilting you into buying it" wasn't there, but I did pick up a copy, and if it looks like it might be up your alley, I'd recommend trying the demo and if you like it, buying a copy as well. They obviously could use the extra sales.