as I load the game the one thing I notice is the unique graphic style, which is refreshing, however the 'New Game' and 'Continue' buttons are rather small, I would suggest making them thicker and making the colours when you run your mouse over them a single colour, other than that the main menu is very simplistic and easialy navigatable.
You should change the colour of some of the text, the sprites or move the text over the black space because you can barely make out what the text says since they are both yellow.
This happens with multiple sprites I have seen so far.
When you get to the bull looking boss, the hit box is way off and it takes forever to find out where it is, also the gap of the red tunnel thing is too small and the red wave happen too often happens too often, however I find the difficulty for the a boss once you get a strategy down is nearlt there, just alittle too hard without anysort of upgrade but as it is the boss has too much health and the player looses health way too quickly. I beat that boss once but I don't think I could do it again
I havn't had any errors, however I get did get a random point where my game froze and so I had to restart the game, It might be a good I dea to try and imploment load points incase that does happen again. (I think I got stuck in a wall or something, but I don't know how)
Another suggestion that I migth make is a run or escape feature, because it have found myself in a situation where I have accidentally ran into an enemy, and you just can get away unless you have bombs. Also some of the are way to quick, you can barely get any pixels before they zoom of in another direction.
other than that the game has been great, not too hard and not too easy, a fresh, simplistic design with music that suits it, with a easy to follow story that is also very in depth. I would say that one of the more challenging parts of the game is remembering which parts you have and haven't been in. Great job good luck for the future.
I hope this is sufficient.