General consensus is, game began as free then randomly they updated from version 0.3 to 1.0 full release and priced the game at $15. People rightfully called this out telling them that there were tons of bugs that needed to be fixed before they should even consider making people pay for the game.
Devs must have planned this the entire time as they sent out a message about how they were quitting game dev to focus on school and thanked everyone for the support. Then proceeded to completely nuked all their social media and discord server before anyone could ask questions.
From then on, they've been coasting on people buying the game in a barely functional state while moderating this comment section for any mentions of "less than legitimate" means of obtaining the game.