an all-around polished game with lots of length

I like the idea of a train struggle, reminds me of Infinity Train a lot. For the gameplay, the bullets are too hard to avoid and the duck doesn't seem that efficient either, the jump also feels too slow. Once these things are taken into account, the player's bullet speed and fire rate should be sped up. That gives empowerment to the player and distinguishes him from the enemies in the sense that he's powerful than them. Lastly, some audio for feedback as when enemies are hit, and when bullets are fired can also be a nice touch. If anything, check out this video on how to make your game more appealing:

Really nice and underrated game. Animations are smooth and the game feels amazing to play. Can be really hard to dodge sometimes, but the checkpoints makes the game more forgiving. Great work!