One I missed from early last month, the action-RPG Lucah: Born of a Dream added a Linux version not long after the initial release. The art style is really crazy.
Make Sail from developer Popcannibal is a reasonably promising game about building boats and attempting not to sink. The latest update is out and adds in a creative mode.
One I spotted recently, Behold Studios (Galaxy of Pen & Paper, Knights of Pen and Paper) are working on a new game called Out of Space and it sounds interesting enough.
After waiting since last summer, Behold Studios have now managed to add official Linux support to Galaxy of Pen & Paper along with the +1 edition free update.
Klei have been working on improving Mark of the Ninja: Remastered with a recent beta that's now live for everyone. Two Linux-specific issues were found and fixed.
Planetary Annihilation: TITANS, the massive scale RTS now being continued by the new Planetary Annihilation Inc had another small patch recently to further improve it.
Since Steam has relaxed their content policy lately, Meltys Quest has not only become fully uncensored it also now has a Linux version so you can go about and do the naughty.
Re-Legion should be an interesting RTS, with a cyberpunk influence you will start your own cult and begin amassing followers. It has a release delay along with a new trailer.
Valve emailed us to let us know they're going to be running an Artifact Preview Tournament this month to show off their built-in tournament feature using their new streaming service.