Fun! This was definitely more reaction-time oriented than the first game, but there is still the puzzle aspect alongside it.
I think there's a lot more mechanics involving the blocks that you can add if you decide to make more of these games. One way blocks, gravity flipping, bouncy blocks, elevator blocks, pushable blocks, blocks that fall down one level every time you jump on them, etc.
Also more enemy types - like one that shoots block-destroying projectiles but only if you alert it, a turtle enemy that can be stood on if you come from behind, but is spiky if you come from the front, a moving enemy that turns blocks into coins, etc.
And things like different colored keys or new obstacles guarding the chest.
Something that would be nice is knowing both scores needed to beat a level beforehand, instead of the ??? . Buuuut I can see that his might give players too much of a hint, as it sort of tells how many of each block need to be used to get that score. So maybe its fine for the player to figure it out themselves.