This is a good, calming game, similar to A Game About Digging a Hole, but:
- You might want to work on the game's visuals. At the very least, you should add some visible differences when the player reaches new upgrade levels. It's good that Giga and Mega increase the size of the drill, and that's visually noticeable, but the upgrade process itself isn't always visible
- On the last level, after buying all upgrades, there were some small FPS drops, both in the browser version and on PC. This is especially noticeable when Tesla Coins are active
- Also consider a version with progression downward (if you plan to develop this idea further and add some kind of ultimate goal). I recommend adding layers of earth that visually take you deeper and deeper. Finding various items along the way down would also be welcome