The name and visuals are all on point here 
There isn't much to complain about the gameplay, it does everything that it needs to do. A lot of the problems you went over stem from the physics programming for the character which can cause certain types of bugs, Given the limitations, a key suggestion would be to think about adding parameters to your game to expand content. Changing the movement speed of the enemies, firerate, bullet size, etc can all be mapped to parameters in your code. You can expose these parameters to build more content for your experience without a ton of work.
This was my favorite game you've made so far! Things are ramping up pretty quickly for you, good job