Carousel
A bus depot puzzle. Every board is proved solvable before it ships.
The yard is full of buses facing every direction, and a queue of people is walking the loop outside it. Pull a bus out into a bay and whoever is waiting in its color gets on. A bus can only leave if the way in front of it is clear, so the order you pull them in is the whole puzzle.
Clear the yard and everybody gets where they are going.
The promise
Games like this usually sell you a way out of a board you cannot finish. That only works if you are never sure whether the board was winnable in the first place.
Every board in Carousel is solved by a search before it is allowed into the game, and the shortest answer is recorded. So there is no doubt to sell you. If you are stuck, a coin buys the best move. The game solves the board from where you are standing and hands you the first step of the shortest way out.
Price
The first twenty-five depots are free. One payment unlocks the rest. No ads, no energy, no timers, and nothing for sale that changes whether a board can be finished.
Hints cost two coins, and you get ten free the first time you clear each depot.
Help
Something broken, or an idea? Get in touch. Also worth reading: what Carousel does with your data, which is nothing.