So, I have to say right out of the gate I didn't spend all that much time with Luminous. I wanted to, but it felt like the game was fighting me.
The art and music are gorgeous, I love the high contrast pixel art, the color cycling in "luminous" form and the character designs are on point, endearing for the player and the sprite, and offputtingly creepy for the enemies.
My issues start to arise with the platforming and controls. The combination of run, jump and luminous is fine occasionally, but when you have to make a triple button press your second most basic form of movement it gets tiring very quickly. Secondly is the character momentum. The character feels a little loose, like when you stop pressing the input and when they stop moving are only loosely attached. With the sheer speed of luminous form and how small a lot of the platforms are, it made for a lot of falls that didn't really feel like my fault. It wouldn't be a huge issue, but since some of the movement is tied to a finite resource that is required pretty often it quickly snowballs into a larger problem. Third is our little friend the sprite, he talks wayyyy too much. Tutorials are fine, but repeating the same tutorial after each death makes my ire for him grow pretty quick.
Lastly is the combat. A single sword swing is okay if the enemies are designed to work in tandem with it, but the only ones I came across bum rushed me like a meth head on a black Friday sale. Since the movement system has no real defensive capabilities and the sword swing isn't fast enough to keep them at bay, nearly all of the damage I received did not feel like it could have been avoided outside of jest waiting and cheesing the enemies. Adding a block or dodge would have gone a long way to mitigating this issue. I speak in more detail on it at the end of the video.
I think you're onto something here, but it definitely needs some tweaks, extra mechanics or rebalancing to be something great.