Push every box onto a marker. You walk into a box to push it — and that is the only thing you can do to a box.
Arrow keys or WASD on a keyboard. On a phone, swipe the board in the direction you want to go.
A box only ever moves one square, and only ever away from you.
Walking away from a box leaves it exactly where it is. There is no rule that undoes a push, which is the whole difficulty of this game — a box shoved into the wrong place stays there.
Two walls meeting means the box can no longer move on either axis, so it can never reach a marker. The game outlines it in red the moment it happens rather than letting you find out twenty pushes later.
It only says so when it can prove it. Silence is not approval — there are other ways to get stuck, and the game will not pretend otherwise.
Tapping a square next to you is a move in that direction, box and all. Tapping further away sends you the whole way there in one go.
That shortcut is always safe: a walk never touches a box, so it can never put you in a worse position than you were already in.
Undo costs nothing and is not counted. Trying something, seeing it was wrong and taking it back is how this game is meant to be played — charging for it would only make the sensible way the expensive one.
The par shown is the fewest pushes the room can possibly be solved in, found by searching every position. Match it and you have found an optimal solution — there is no better one to find.