Ooooh Nice intro music and text sounds!
The transition to the main game screen looks great too, it matches the style of the game ( in my Opinion ). I guess the games UI was inspired by Shovel knight? : )
I would also strongly recommend adding a text ( Animated ) which tells the players which key to press, ( especially for much newer players getting in to pc gaming ).
One thing i really liked about the gameplay was the fact everything was unlocked right from the start, it was awesome to simply press the spacebar and see my character dashing through enemies without taking damage although in some cases, some where along the later stages i found myself landing straight on the enemies and taking damage having nothing else run through my mind other than ( This could really use some double jumping and or a shoot mechanic ) its a really god thing you added the checkpoint system, that was quite thoughtful. Nice touch!!
I also thought it would also be a good idea if the enemies didn't move as fast as they did mainly cause the characters damage range is relatively cute.
After my first kill, i immediately imagined my knight with a massive sword and a side arm cause i'm a huge nut for massive humongous swords that deal crazy damage and fast gameplay. XD
In all, Nice game, im looking forward to seeing a complete version of this. Great game!