So, I could not get this to work or understand what was happening.
I tried to get it working for two players, but it didn't work.
The sound effects sounded like I was picking stuff up and hitting stuff, despite nothing being on screen.
I thought I picked up a bunch of the green things, but the game says that I didn't
And it was a bit hard to control.
I really like how the game looks. I think you did a great job creating a game and a style with four colors that doesn't feel like you compromised anything by only using four colors.
It's a decent start to a cool game, I think that it needs some polishing. And I would say trying to focus on a better single player experience could be good as well.
And if you want to completely rework the entire game. I think this could work as a cool underwater exploration kind of game instead of an arcade like game. But that would be reworking what the game is about.
One other thing is that when you click play game, it freezes for a bit. I can assume this is the game loading the main game scene. I would recommend having some kind of fade out from the title screen and fade in into the main game to hide this loading.
Overall, cool looking game. Just wish either it worked, or I understood what was happening.