Pretty cool game, smooth movement and well-polished experience, nice job! The psuedo 3d perspective is really neat and an impressive feat in a 2d engine like GameMaker. It gives the game a really unique feel (especially when combined with the slightly trippy background) but can have make for some frustrating gaming moments as it is really difficult to tell when you can still shoot the enemy and when you will lose a life. The boss fight was a super cool addition and a very welcome surprise. The sfx and music fit the overall vibe well. I think having some sort of mechanic to prevent the player from just holding down the shoot button would have been a good design choice. For example, an overheating mechanic that requires the player to stop shooting for a bit to cool down or else they get locked out of shooting completely for a few seconds. That being said, your game has a very unique aesthetic paired with smooth movement and a cool boss fight. I dig it. Good entry, and keep up the good work!