This is all nice and stuff, until you get to World 3. I absolutely hated the world. It has one of the most overpowered action in the game : it pulls a column of blocks upwards. I don't see any practical way to beat it without having one heart left.
There is also the dragon boss that has magic defense and an ability that makes the blocks unmatchable. You can still destroy the blocks using the missiles, but they will always target the blocks at the top.
Speaking of magic defense you really had to make it only usable to magic attacks. It's one of the rarest blocks in the game too, making it even worse to play. Also regular attack blocks are just as rare.
So in order to beat the game, you need near-perfect RNG. If you don't have good RNG, then the game is impossible.