There are a lot of issues, and I didn't even make it past the first spikes.
1.) The UI and key controls are annoying. only Enter advances things, it should be any key.
2.) You get offered to buy hearts right when you start the game which is always impossible, and shouldn't happen.
3.) I get the controls but they don't work very well, and as I said, didn't make it past the first spikes. Players have to have a good first impression or they'll never return no matter how good you make it later
4.) Update, I tried again and passed the spikes, the sword move isn't bad, the spike hitbox is very unforgiving.
It could be a good game but I think it was released too early, needs a lot more, like different powerups, achievements, something. Keep it up, this can be better!