Hello Jellyfish! What are the usual distros that cater to games in Linux? Admittedly we're not that experienced in developing for Linux but we'll check it out!
I'd say if it worked on Ubuntu you'd be fine.
Steam requests support for Ubuntu 12.04 although a lot of developers tend to aim for Ubuntu 14.04 these days since 12.04 is a little old and there are some big differences between the two (though mostly for 64-bit but that's what most people use on Linux these days).
+1 For Linux. You might want to look at AppImage. Using that you won't have to worry about Linux distributions as much.