As part of Humble’s “micro Jumbo” Bundle, they are giving you DRM-free versions of Space Pilgrim Episode 1 and Pony Island for free
(note, not steam keys, but drm-free version, steam link only used to easily show you games mentioned)
scroll down middle and enter your email and they send you a copy/download link
(you don’t have to accept their newsletter if you don’t want, you can just uncheck the box, and with or without you still get the games all the same)
PS. Pony Island has Win +Mac+Linux support, Space Pilgrim so far only has Windows supported