I downloaded this game and beat it (reached the final level) within 1 hour. I had over 82 “drones” $900mil.
After reaching the bottom level, my drones dove into the bottom level and never returned, if I purchase more drones they simply dive and never return, no money gained. I do not know if this is a glitch or part of the game.
I would love to continue playing once this is fixed and more levels are added. Other than the “glitch” explained above, the game is very fun and quick. I would say that as you go down the tiers of drones some tiers are useless, for example the last tier, the cost of upgrades is far greater than the tier above, and for less output.
I believe with minor tweaks and more levels this game would be great.
Another opinion would be that after you reach the “core” there should be a option to “prestige,” “travel,” or “time travel” starting you back at the beginning with a “dig” multiplier. And possible “rubes,” or “ores” that could be found while digging that the player collects, and uses to upgrade “permanent upgrades” that “prestige” with the player.