They Came From Above

Wave 6 has the first variation, but it's just a bigger, slower, tankier enemy. The actual difference is unfortunately negligible. It is still a passive falling enemy that does not maneuver or do anything interesting.

Moves too slow

By wave 5, the lack of enemy types, the constant shop popup without being able to afford anything, and the slow pace make this game feel much worse than it is. Simply adding a second enemy type that can move side to side at any speed would double the available content... from the perspective of the early game. If there are more types added later, then they need to be shown earlier.

I quit at wave 13. Too easy and boring.

The upgrades are too expensive to start. You can't buy anything until around Wave 5.