Let's trade feedback! I submitted a project too.
- Mechanics: Great interesting level designs and combining the power-ups. I like that your level 1 serves as both a tutorial and a simple level to easy the player in, without needing over-explanation.
- Art Style: Good use of the platformer packs. Fairly straight forward. There is a few glitches to fix. The particle effects sometimes glitch, when picking up powerups or the key. Also the blob enemy gets stuck on the doors at time or parts of the level itself.
- Level Progression: Level to level difficulty felt fine. The level with multiple powers felt the most fun. I like being challenged to time my jumps instead of usual platformers you can jump anywhere at any time like Mario. You've turned platforming and powerups into more of a clean puzzle experience.
- Recommendations: Hope you keep building on this. I don't think you need blob enemies at all. Use the level itself and environmental obstacles to be a danger to the player or helpful. You could add helpful terrain or dangerous terrain. You could add traps that require using powerups in a certain order. You could taller levels, wider levels or themed levels that match new power-ups. Use your level design skill well to make the world feel like it can help you or delay you but without the need for in-level blob enemies.