You seem to have placed a great effort in the weaponry. The pixel art looks great. 7 days to make a game IS a crunch, but you have a cool idea and you can expand on it after the jam :)
- As others said, add helper UIs in-game or add a tutorial scene to help players understand the mechanics.
- Your game page tells a story so a bit of dialogue can make the game interesting as well (e.g. "This is mine!", "Back off!", "Take that! No.. That's mine. Give it back!")