Hey, Minga! Thank you, thank you! Yeah, the word hard/difficult came a lot this time around! But I'm already working on the game again, to solve this. I'll make it more friendly and "fair" to new players. During development, due to the time schedule, I had to make "harsh" decisions about a lot of things, and that includes the behavior of the bosses. It's not like I wanted to make them difficult. I just went full pragmatic in order to deliver before the deadline. That said, it's actually a very easy thing to fix, and I'll do it!
Actually, I believe you can to map the movement to WASD. I just did it here on the web version.
Cheers!