Just happened upon this game by chance. Really nice, though I thought I'd post a few problems i personally experienced playing it. These may be fixed already, but i'll list them anyway. (Keep in mind, I am by nooooo means a programming pro. In fact, everything I personally know about coding i learned from a friend, and am still learning. Not to mention, its GML.)
-Maybe I just missed it, but well... there's no apparent way to... "close" the game. It automatically starts up in full screen, and alt+enter doesn't exit full screen. I either have to call up the task manager or beat the 3 stages you have. (And I imagine the game itself will be much longer, soooo... not being able to exit the game is kinda problematic lol.
- I wasn't able to reproduce it, but i ran into a bug where if you died and attacked and killed an enemy at the same time, the game wouldn't restart, and you'd be frozen in place. (That's how I found out about the above problem, because there was no apparent way to reset or close the game)
-This may not be a bug, but I noticed that you can't jump over walls if you're touching them. Is that intentional?
-This also may not be a bug, but I also noticed that our Prince's sword has 'quite' the range. It can even attack enemies that are behind him. I don't think that's intentional, but hey, maybe it is? Maybe the prince is also a psychic ninja lol XD.
That's about it. Everything else is really nice! The graphics are really nice, the atmosphere's just about the right amount of creepy, and as simple as it is, I loooved the music.