A random shot in the dark of mine, but it seems to the developer of JASEM [Steam, Official Site], the self-described 'insanely hard' twin-stick shooter could see Linux support.

About the game:

Do you need any reason to shoot your enemies in game? Because JASEM doesn't give you one - just you, your weapons, crazy beats and enemies. And you need to shoot every one of them, and it's up to you to make it the most hilarious and explosive way.

Here's what the developer said in response to my query:

Hi, sorry for slow response. I made Linux version, but didn't find the way to test it - and it could be various problems with shaders and performance, so until I find testers I can't release it.

Pretty positive response! So if you fancy testing, let them know in the Steam forum post.