Puzzle Lab
Every puzzle says how many moves it can be done in. Can you match it? You can undo, start over, and ask for a hint. There is no timer.
For grown-ups
A series of move-and-think puzzles with everyday things: tilt a box so the balls roll out of the hole, turn pipes so the water reaches the flower, slide cars out of a traffic jam, sort fruit into baskets, get everyone across a river. Every challenge says how many moves it can be done in, and the program has checked that is the true fewest. There are eight challenges at each of four sizes, undo and a hint on every one, and no timer. They practise planning ahead and picturing what a move will do.