Hey I realy like the basic concept of this game, I do have some points of improvement,
I don't really see the purpose of "gizmick" the little animal to keep alive, why is he even in the scene and why do I need to keep it alive, it doesn't serve a purpose. Maybe you could've added an ability to him to make him more usefull.
Second the movement doesn't realy fit the bosses, the first boss was easily defeated by standing in one spot and hitting him while he comes down on you. the second boss the same but step away when he comes down.
The third boss I think I didn't really understand, you get a dash but when dashing through it's first attack he instantly kills gizmick I didn't find a good way to solve this problem and ended up defeating him by just hitting him fast at the begginning but this felt more of a cheese strategic than actualy beating the boss.
I really like the art style and the sound you put into this game, congrats on the game and keep going!