What a neat experience! The asymmetric gameplay took a bit of thinking, but with the limited options available to you, I didn't find it impossible to figure out. I loved the idea of sending things back and forth. The final bit with the checkerboard box was pretty clever, though that might be the only thing that needs some visual clarification--the portal looks more like a visual effect than an interactable.
Loved the self-made sound effects, too! Overall very fun and enjoyable to play once you get the coordination down of manipulating both screens.