I'm not sure that I fully understood Mind Game. I left it a bit confused about a moment near the end that echoes a moment at the beginning. Regardless, this is the sort of "roller coaster" experience that I can get behind. It's zany in the best sense, exploiting (in a good way) the uniqueness of animation's ability to present the impossible. This film could not exist as a live-action film. Maybe it could, but the director would have to hire a whale.
Surprisingly, my favorite moment in Mind Game is a delightfully obscene moment of a young man squeezing a gun barrel with his butt cheeks. That this moment is astonishingly life-affirming is a testament to the ridiculous greatness which this film often achieves. I could quibble about other moments which I disliked, but I won't. For the most part, I was thoroughly caught up in the game.
I'm glad that Arthur brought this one to our attention.
I also watched the original pilot for Adventure Time, but don't have anything to say about it except that Jake downloading something from the Internet with his mind made Abigail giggle.