I like this charming little game! The pixel art aesthetic is awesome, and the subtle movements of characters really make it pop!
If I may, here's a few suggestions:
1. The music, while great, was a bit loud, making it difficult to hear the sound effects (which are nice!)
2. It's a bit hard to guess when the Nightmare Knight is swinging - sure, you can block while he's swinging, but there's no way to know when he starts swinging. Maybe add some kind of indicator before it swings? (e.g. it turns red or something)
3. The same slight issue is with the Nightmare Knight dashing - you can't predict when he'll dash, and when he does, given how fast he is, it's basically a life lost because he's nearly impossible to dodge - an indicator before he dashes would be nice
4. I'm not sure if that's intentional, but when I dash, I only dash downwards, so I don't really use the dash
5. A really minor thing that has no impact on gameplay, but maybe the direction of the knight horse character can change depending on where you're moving? Currently, he only ever looks right.
Other than these nitpicks of mine, this is a really cool little game!
Do you intend to keep working on it? What sort of features would you want to add?
Keep up the great work either way!