This game was one of those, that I played as a child, and just replaying it basically right before this review, I don't think I've ever beaten that one before, 'cause boy is this game unforgiving.
The hit boxes are sometimes totally weird and then there are these cool "?"-Boxes, that whenever you break them either have a cool power up.... Or a miniature death that is chasing you and will get you 99% of the time to insta kill you. Which is btw. everything in this game. Every thing insta kills you. Unlike Mario games or Sonic games, there is no way to withstand a single hit by an enemy.

I liked the Level design at first... But then the last levels came around. Suddenly you have to do annoying types of jumps (for example the one upwards, where you have to break blocks first) and suddenly there are rooms where you have to instantly react or die (for example the flooding room) and the last puzzle was just like... What??? And doing a single mistake (even by mistake) spawns one of those miniature deaths in. Nice!
It doesn't help, that the ending really feels unsatisfying after going through these last levels, as it is just a wall of text, telling you how Alex saved everyone. Not even a little cutscene showing this.

Nostalgia and first levels save the game, but the ending is just meh.