I really liked the game to start, but there is a bug that makes the game quite unplayable. When upgrading tools one can collect materials faster in the game, however, when upgrading the pickaxe, the most basic ore mines faster but still gives 1 ore. This means you have twice as less ore to collect in the game. I tried to find a place in game to report a bug, but I couldn't find it. I hope the devs fix it soon.