This is a creative take on being "joined together", but I feel like you get all you can get out of this game in about five minutes. Which, I guess, is fine for a jam, but maybe having some different level layouts or different rooms to travel to would help give the game a bit of purpose. Or just something to occasionally change the status quo beyond just more monsters appearing.
Also, I do feel weird about the bullets travelling in the same direction as my dash, as it often has me careening directly into enemies. If your goal is to create that kind of risk/reward scenario, that's fine, but maybe have the bullets move faster than your dash so they are ahead of you and hit the monsters before you would help make the game more forgiving. Otherwise, try having them go in the opposite way from the dash so the monsters can kinda "eat your dust!"
One small thing I do want to thank you for is the initial delay before sending monsters out at the start of the game. You added just enough time to kinda play with the bullets and try them out before the monsters appear, and that is a really nice touch for at least getting players started on the right foot!