There is a good concept there! Mechanically it's quite dynamic and fun, and having the bullets also move the player is certainly a great idea to add depth!
To make the game more interesting it could have some difficulty progression, enemies appearing faster and faster, and a score tally for players to compete against each other :) Even, with more time, slower enemies but needing two or three bullets to die.
48 hours is not enough time either, so, good job!