This is a very ambitious game! You should be proud of yourselves that you managed to finish such a big project on time! Great job!
It does feel a little bit unfinished at times with big open areas, billboard enemies and very sudden level transitions. Still, the game is functional and fun, I didn't encounter any technical issues and had a blast playing.
As for things that could have been improved without massive time investment, I think that the section with the ghost is too long, it's like half a game long... I would prefer more levels where I get to shoot bad guys. 😁
Good luck with your future projects!