Smintheus, a sweet 2D puzzle adventure game with crafting and survival elements that's currently free during the Beta added Linux support recently.
Initially, it seemed to be quite a basic game, but the introduction is very deceptive. It gradually introduces more and more gameplay elements pulled in from different genres. The game involves linear exploration, crafting gadgets, avoiding traps, doing quests to progress and more. It's quite unique, so it's going to be interesting to see when it's finished.
I've spoken to the developer, who said they're hoping to finish the game sometime around August where it will be a full paid-for game. The developer is after feedback, so be sure to give it a whirl let them know what you think.