This has a lot of potential, I can imagine an awesome soundtrack and some gameplay tweaks this being a ton of fun. A few notes from my game. I didn't have a clear objective, so I assumed I should just survive as long as possible. Perhaps displaying a timer counting up would help reinforce that if that's the case, so I can track how well I do between runs. Also, I backed myself up into a corner and it was pretty easy to flail the sword around so I didn't have much incentive to move around after that as I could kill anything near me quickly. Perhaps some enemies with ranged attacks would help push me out of the "safe" area, or have powerups/objectives spread around the level I need to go find.
Overall very fun!