nice job! Props for making everything from scratch! It's not the most polished game, but it's functional and honestly no game breaking bugs! The bugs it does have are minimal, like the jump not being high enough, so you kinda have to jump on the side of the wall to get up in the first level (not sure that was intentional, but I think it'd be better to have the jump be higher and less "floaty").
I really liked the slow motion effect! It's done really well and helps a ton when there a million bullets coming at you! XD that said, maybe it would be better to have YOUR bullets not effected by it, because then you could avoid the bullets while also killing enemies faster. Overall, good job on this!