REVIEW:
I just finished this game, playing together with my brother, and we had a blast. (Surprise twist: we're both in our forties.)
I think all the levels can be finished when playing alone, but with two players it's easier. Or is it? If you're not communicating and following a plan, you're sabotaging each other just as much as helping, and that's hilarious.
Anyway, there are eight worlds with ten levels each, and a lot of different puzzle mechanics that are introduced and explored nicely throughout these worlds. It's an entertaining puzzle action game, with a lot of variation.
Some small constructive criticisms: there are some difficulty spikes: levels that might have you stuck for a long time, without a way to continue to the next world, so some perseverance is needed. The colors are extremely bright, saturated and mostly primary (like bright red, green, yellow, blue). In some levels this actually hurts the eyes, especially when playing on a good screen like a TV. I don't mind the cartoony, child-like look, but slightly more modest color schemes would have been nice. Finally, starting the game with two controllers is somehow a bit finicky, but we did manage every time.