The concept of the game is quite interesting! It's quite fun too. I think the design could use some polishing. Having to switch from using the knight back to tetris mode at the same time is a bit awkward. Maybe you could fix this by doing phases? Example: Place three or four blocks THEN only use the knight. And then repeat.
Aside from that:
- I noticed you can't click on the retry button when you die or the continue button after finishing the level.
- A warning when you're about to clear a line with your character on it would be useful.
- I would make the AP count pop out next to the character (like you do with the HP when you take a hit) every time you make a move so you can easily how much you have left.
- The hit sound that plays after attacking could be softer so it's easier on the ears. Add some random variation to it too.
- Add more music. I'm getting tired of this one song playing on loop as I'm writing this feedback.
- The aesthetics of the game aren't bad but all beige/gray/black is a bit boring. You should find a way to make the color scheme more pleasing to the eyes. Maybe add a colorful background instead of the black void.
How much time did this take you to do? If you fix these small issues the game isn't far away from being to ready to sell.