Thanks for your comments, I am glad if you had a good time!
First of all, using some "shadow" to indicate the uncollected cards is really good a suggestion, I just marked it down, and it will definitely be implemented in the next update. By the way, there are 9 of them.
Many people have complained about the Crate part, my poor physics implementation causes lost of weird bugs, which introduces some unpleasant experience. More efforts will definitely be made to find better physics interaction paradigms.
For the portal, I tried to set a "half-predictable" design principle. Most of the time, I want to make it possible for player to infer the connected portals based on the color and edging direction; with few trials, a non-linear moving line should be drew in the head. On some occasions, portals will teleport the avatar to a totally strange place to start a new adventure, but which also would be turned out to be closely connected in the whole map. The level design would be focused and improved when designing the Post-Jam.
Thanks for your detained feedback! Hoping I will publish a polished version in the future!