This is an older game, originally released in 2013 for Mac and PC. The game itself is fun in its own right but a bit repetitive. I enjoy going back to it on steam every once in a while. The reason for the 1 star is the monetization. What used to be a $5-$10 game now has in game purchases to expedite unlockables. Sure it's free up front but there's an actual currency doubler you can buy with real money. A purchase that acts to speed up slow progression purposely added by the app developer. Scum.