How it works
Pick a colour and tap squares. The fold line is drawn so a child can see where the
picture folds, and the given half cannot be changed — tapping it says so.
Nothing is marked until the second half is as full as the first. Then, if it is not a
mirror, the game says how many squares are still wrong rather than which, so the looking
is still the child's job.
Four sizes, and the third folds across rather than down. That is much harder to see,
which is why it is not the first one.