I have such mixed feelings about this game... I love the concept, and the feel of slamming down into the Earth and seeing it rupture is awesome. But the difficulty feels very cheap and completely unnecessary. The bullets are tiny and very hard to see, getting hit while transforming feels out of the player's control more often than not, and even with debris, sometimes it all just gets eaten up and suddenly you're super vulnerable with zero margin for error to survive. It's incredibly frustrating when you reach the stage of becoming a super huge, tentacled, Earth-destroying fiend of destruction... and then you get dinged by a tiny bullet and it's game over. That just feels so, so bad, having what's supposed to be incredible power only to be undermined by something that shouldn't perceptibly be even remotely close to your power. The entire game is building up to that point and yet it ends up being the most frustrating part of the entire experience.
I see that "bullet hell" is part of the description, but the screenshots and premise of the game don't give that impression at all. In fact, I'd say the bullet hell aspect of the game detracts heavily from what it makes it so great. Even if the game was a total pushover, who cares? You're an unsettling, planet-busting, otherwordly entity destroying the Earth by slamming into it and gradually growing into a colossal size. It's a super cool concept, and the feel of this game was nailed so perfectly that even if it was mindless rampaging with no challenge whatsoever, it'd still be so incredibly fun.