Ah I see!
Looks like I got everything together. For some reason the crosshairs are awkwardly fixed to the top left corner when you full screen, and the minimized window size makes it hard to aim and pick up. This may have to do with the mouse support, but the rifle only picks up with the right player, and the left player has a hard time picking up in general.
Thanks for the rating my game by the way! If you played and ended up liking it, feel free to leave your thoughts in the comments (even if they're bad lol).
I think with some extra polish and those additional maps you mentioned, this will be a cool game to play with someone else!