This starts out as a rather nice, straightforward idle clicker. Unfortunately, it drops off, and drops off HARD.
By the later parts of the game, you get bottlenecked by the ATK requirements. Unlike the other stats, it's an all or nothing - either it's high enough to apply your damage to a planet's HP, or it's lower than the planet's defense and you do nothing whatsoever.
Skills won't help either - by this point, you've probably experimented a bit, a few points here and there, and that means your level barely goes up once an hour - the game doesn't really do anything if it isn't open either, so you have to at least have it running off to the side. You can't try anything to fix this - there's no button to reset skills. Even if you're willing to try again from the start to change the layout, too bad - there's no reset game option either.
There's also no other modes or new stuff to change things up or hold your attention, so it gets dull after a while. You're just left killing thousands of the same planet, doing way more than its health, barely bothering to upgrade DMG because of this, rarely bothering with AUTO just to try and reduce the wait cycle, only upgrading the once-powerful BOLT just to hit that last achievement that doesn't really give enough xp to help the skill point issue, just waiting until you can upgrade ATK one time to move to the next planet. When you do, you move on to the next, previously damage-immune planet - and immediately repeat the same cycle again.
That's all there is, and you can't do a single thing about it.