Probably too low. Games shouldn't be priced under $20, it's a shame that game makers have to do that to comply with expectations set by a terrible culture created by mobile stores and constant discounts.
To be fair, that's less the effect of a race to the bottom and more the explosion of options in recent years, weighed against a game's complexity, potential spectrum of appeal, replayability, and the finite capacity of the public's bank accounts. After playing it, I can only liken it to TowerClimb; a similarly impressive low-priced roguelite pixel-based labor of love with an incomprehensibly high difficulty curve that, at present, is going to ultimately limit its potential audience.