Remember a year back when those Linux Steam builds leaked, everyone went crazy, and then nothing happened? Yeah. Well, it's happening again, except this time with Desura, and the Linux client actually exists:
You can browse, buy, download, and play games. Any games that you've previously bought for Windows will show up here if there is a Linux version available as well. For games that support it, you're even given a choice to download a 32-bit or 64-bit version. I don't see why it shouldn't just always use the target architecture if available, but choice is nice.
Overall it runs well, sits in the tray when idle or downloading, and (somewhat) integrates with Unity (i.e., it adds an exception for itself in the tray :-P). It does have some trouble with the Unity launcher though, and spawns multiple icons if you try to pin it. The download is a single binary that bootstraps the rest of the installation into a desura folder. Additionally, the client auto-updates, so it's not very suitable for packaging. Hopefully the Desura team is open to making it available as a system package later on.
Currently the Linux build of Desura is in closed beta, but if you want to join, sign up and request to be added to the Desura group.
Something Almost Completely Different
While we're on the topic of Linux games, check out Spiral Knights. It's a free-to-play online action RPG that can launch from your browser or be downloaded. I've been quite addicted to its simple nature and the fact that you can pick it up, play for a few minutes, and stop easily.
The game runs with a few tiny quirks on Linux (fullscreen sometimes doesn't work, and same Unity launcher bug as with Desura) but otherwise it's just as playable as its Windows counterpart. It's running with a little modification that I made to force anti-aliasing on NVIDIA cards: see this gist for a launcher replacement you can use.
Steam note: If you want to play Spiral Knights on Linux and Steam with the same account, do NOT convert to a Steam account, otherwise you will be unable to login on Linux. I made that mistake when initially starting the game, and now I'm in touch with support to try to reverse that.
Also, Legos
And of course, there's Minecraft, which is running better than ever with 1.8 and the 1.9 pre-release. Not much else needs to be said here, I'm pretty sure everyone reading this knows of the game. And if you don't, well... go try it.