This is one of the strongest implementations of the theme that I have seen! It would have been easy to just subtract points during the stage and show the final score at the end, but you really hammered home the penalties with the game-end summary!
The procedural terrain + checkpoint generation felt fair and organic! And in particular, it always felt obvious exactly how my jump works, which is a huge problem in a lot of top-down scrollers like this.
I wish the game got a little harder over time, either with faster scroll speed or more dangerous obstacles. It feels like I could play this forever once I mastered the core loop, so I think I would have much more of an incentive to chase a high score if it was progressively more difficult over time.
Nice work!