When trying out Flux Caves myself back in March, I was quite impressed with the demo. It recently released in full and as of today, the Linux version is live everywhere.
Unlike some puzzle games, the aim of Flux Caves is not to make you sweat or get frustrated. It's supposed to be a more peaceful experience with a slightly open-world for you to run around in. There's no losing, no dying, just you and the puzzles.
The gameplay mostly involves you pushing blocks around and connecting things up, so balls can reach from one end of the puzzle to the other. So it's like playing with giant marbles, well sort-of anyway.
Previously the developer did note they had a few issues sorting the Linux version, but as of today it's live again. You can pick up Flux Caves on both itch.io and Steam. Curiously, it seems the version on itch is quite a bit cheaper, although itch does allow you to donate extra.
There is also a demo available on both stores, good to see more developers allow players to try before you buy. I miss the days where everyone did that.