This is a great platformer. It manages to incorporate Kirby, Mario, and Mega Man under one umbrella both in gameplay and aesthetics. I would say, however, that it being a mobile game which is dependent on touch controls does hamper the experience somewhat. I've had instances wherein my finger accidentally slid against an onscreen button as I was repositioning how I held my phone, causing me to lose a life. While I don't think this can really be helped due to the format, I think it can alleviated by somewhat more frequent checkpoints or the removal of a lives counter (though it doesn't seem like that is actually in effect in the demo, which was nice). I'd also say the physics on the final arc of the jump feels off in either animation or in how the transition from an upward trajectory to a downward trajectory affects the speed (I think it maybe feels too immediate. It might also be nice to have a unique frames of animation for when the peak of the arc is being reached which can transition smoothly into the fall). There are also a few instances of unavoidable unseen damage, like taking a boost pad upward into an enemy that was off-screen. Also, some enemy hitboxes don't seem to represent their sprite sizes as some of bullets fired would travel through their bandanas without hitting them.
That said, if this game were to be placed on the store as it is now, I'd still think of it as being relatively ready for a full release so long as the mobile market can forgive some frustrations and play a full-on platformer with touch controls. The artwork comes together extremely well and the music (especially the third stage) adds an enjoyable bounciness to style. One improvement there could be adding character animation or other touches to the overworld screen, though that might already be obvious. Ultimately, the biggest concerns would be adding some slight degree more leniency due to the touch controls, tweaking the physics/animations of the jump arc, and reexamining some of hitboxes and level design to prevent what can sometimes feel like unfair damage. Otherwise, great work!