I really liked this jam. It's the first game jam I've seen that's focused on using the same pre-made assets for everyone who enters, which makes the jam pretty unique. I thought the variety of the assets was pretty good. There's just enough variety that you have a choice of either using them the way they were most likely intended, or combining them and picking apart the assets in interesting ways. The functions available in the carts were also really helpful.
I personally liked the mystery and the rewards from it, which gave me new ideas for what to make (although I ended up not having enough time to use them).
I think instead of multiple themes, there could maybe be one theme based on the mystery itself, so how much does a game reference or build off of the mystery. Just an idea.
The rules could be a bit more clear on what you're allowed to change after submission, like if game-breaking bugs or typos can be fixed.
I'm looking forward to seeing another jam like this one!