The hyperbolically-named Megadrill is a game of persistence. It's one of those grind-heavy browser games where every play grants a small reward to be spent on incremental upgrades that increase the likelihood of a bigger reward.
You drill down into the ground and try to collect gold deposits by steering right and left. You can upgrade your drill's radar to help you spot nearby deposits. You can upgrade the fuel tank so each dive lasts longer. You can upgrade the hull strength so you can withstand higher pressure the deeper you go.
It's really just a variation on those games where, for example, you launch a penguin off a ski jump and see how far he goes, boosting his flight prowess between attempts. Only this time there's an unintentionally topical political message to chew on.