Since the start of the mayor's challenge, the game has become unplayable, at least for its original intention, to build a city.
The marketplace is in need of an update, and possibly also better planning of the challenges. The marketplace is overflowing with only items being created for the challenge, making it impossible to buy anything else. If the various levels of the MC contained tasks so that everything was being created (at least within a two week period) AND the marketplace did a better job of showing items from players at all levels, or at least half of the options came from players in all levels of challenges, this would likely help solve this issue.
I'd also like to see an option to opt out of the mayor's challenge, and doing so, the marketplace would show only items from others who have also opted out. This is another possible solution.