Hellpoint [Official Site] is a good looking dark sci fi action RPG that's currently crowdfunding on Kickstarter, they have a Linux demo ready and they've now put this demo on Steam for easy access.
They keep updating the demo too, so this is a new way to keep it up to date. The latest demo adds in a new big boss fight, to show off the action a bit more.
To me, this is another case of a developer really caring about Linux support. They reached out to the community originally to gather testers which went well. So they decided to do the Linux build! They also included a quote from me on their Kickstarter, which I thought was nice.
You can find the demo on Steam here and their Kickstarter here.
They have 6 days left of funding, with quite a bit left to go, so hopefully they will find enough people willing to support them.
If you try out the demo, let me know what you think of it in the comments!