Fun game, but really slow progress in the end. Game it 5 stars at first. But after playing it for a few days and the progress gets really slow, I changed it to 4 stars. After fully upgrading everything and playing for more days I finnaly realised that the game is endless after I goggled a lot on how to beat the game...It was kind of disappointing. The title kind of implys that there is an end if you reach the core :S
 "Reach the core"){kind=icon}