I liked the mechanic of moving two players at once. However the co-op levels were a bit boring. The switching of controls felt weird and I think that such a thing could have worked better with a vs mode.
As noted by ChaoticAurora the hit boxes were a bit unfair. To solve this I think a grid based system would have fit perfect for your game

The theme however was followed quite well and it delivered some interesting ideas.

You're game is really fun!

I played untill the co-op part because i am only one person :P

i would recommend three things...

- some hitboxes feel a little bit unfair so i would like a little bit more foregiving hitboxes

- You can get stuck by pulling the "sticky boxes" between you and the wall.

- adding a retry button is nice so you don't have to go back to the menu to try again

But i really liked a lot from your game. The retro vibe goes well with the simple puzzle gameplay and the way the features are slowly introduced is very nice!