While we were there, we went to the Independent Games Festival Awards, and there were many interesting-looking games. One in particular that stood out to me was Dyson, because of its elegant, abstract, procedurally generated art. It's an "ambient real-time strategy" game that involves exploring and conquering asteroid belts with fleets of self-replicating seedlings.
The next day, someone talking to us at our GDC booth mentioned that Dyson runs on Linux using Mono! It uses SDL via the Tao wrappers. It doesn't run on 64-bit Linux yet; it looks like Tao.Sdl isn't 64-bit safe. Fortunately, I have a 32-bit parallel Mono environment, which isn't too hard to set up. However, setting up SDL and the dependencies for libgdiplus was nontrivial, so I don't recommend this path.
Anyhow, I got it working. Here you can see an almost-conquered asteroid belt:
And a close-up of fending off an invasion:
It's a lot of fun, and I'm looking forward to the full game's release! It's already listed on Steam with a July 31st release date, and says there that Linux is a supported platform — does that mean we'll see Steam on Linux soon?