Why exactly is Ruby bringing her cutlass to the library? Not important--I'm just glad she did. Awesome prototype (with PHENOMENAL pixel art oh my goodness). Using a sword to block projectiles rhythm-game-style? Excellent. Feels great. Needs more juice and some way to win/lose/end the fight, of course, but I absolutely love the concept and all the flair you've already put into this. Also the KEY!
I hope you keep working on this because I would love to play the full game.