Indiagala offers Steam downloads of Anoxemia for Windows and Mac
when when you join Indiegala's Steam community group and register your email. (Scroll down to find the game.) That's the lowest price we could find for this game by $2.
You'll need to link your Steam and Indiegala accounts to activate the game. (If you don't already have one, you'll need to create an Indiegala account.)