I get a glitch: after one hit on the vampire, he spawns crazy amounts of skeletons that the game lags. Had go on a higher platform to survive, from there I took a screenshot (note the line of skeletons at the bottom): https://www.newgrounds.com/dump/item/5b815020949a3047727e11086ca1448b

Using the latest Opera browser

The music and design are nice. I specially like the char, the way he's slightly crouched, sneaking.