I see your point, especially if you are in just for android version.
But PC version is working. And there was no reports of issues with MAC. And also if you want to play android version there is emulator for PC to do that.
Also you have one more point that there in nothing clearly stating this game is still in development. Stating version number below 1.0 and "future plans" aren't at all clear indication of that.
And on note of buying in there is many reports of issues of 0.2.1 build not working on many android devices in comments. Take this as educational experience because this one didn't cost you arm and leg. But taking bit of a time to research in what you buying/investing in may be worth it in a long run.