Hi! I played your game and I have some feedback:

1. The genre is fine, you can do what you want with it. Making it a platformer might be an interesting spin, if you somehow still kept the Pac man elements

2. The concept has good story quality, but isn't anything particularly new (that's not necessarily a bad thing)

3. The different enemy types and stuff are good additions, maybe a character/powerup selection, or a custom mode?

4. Overall the game is fine! Maybe a little repetitive. It would be better with some kind of incentive for killing the enemies other than progressing to the next level, maybe lore based. I did find that:

• Wall collisions are a little awkward (player backs up a little when colliding)
• Player moves very slowly (this is fixed when in knight mode, but still)
• Grammar mistakes here and there
• When you lose you go all the way back to the home screen 
• Some of the dialogue is a bit unpolished, and the game feels rather amateurish

Other than those, it's good. I liked some of the sound effects (like when you clear a level, it's a funny song lol) 

Have a nice morning/day/night!

The player moves very slowly. This makes each level agonizingly boring. I honestly thing this is the only major issue, gameplay-wise. The slow movement prevents the gameplay from 'flowing', like it would if you were playing something like Pac-Man (The diamond in your game is very similar to that big pill that allows you to eat the ghosts, so I was reminded of Pac man). 

Music is on point though

I haven't played the game, but I noticed it looks like you're using RPG maker assets, but the game is made in Game Maker. You should know that using RTP RPG Maker assets in any engine outside of RPG Maker is against their rules, so I'd suggest switching them out.

(I hope I'm not coming of as antagonistic, I just thought it would be good to know. I doubt Kadokawa, or whoever owns the licence, will notice but still. Better err on the safe side.)