I feel like most of your levels are overdecorated and very few of them focus on a concept and develops it, judging by some screens, some of the levels just look like corridors with the same sets of enemies. I'm just judging by the screens, though, the levels might play different from what I'm imagining or something of the sort, but still, be careful with overdecoration and boring the player.
i never performed a shelljump and it's sad
I did a grand total of 4
shelljumps in my life!