WASD slides the whole board. Each pair of equal seeds can merge only once during a single action.
Directions work on the keyboard or pad; the pad button also acts as RETURN. SPACE opens confirmation to restart this stage. NO is selected initially. Choose with A/D, confirm with RETURN, or cancel with SPACE. Play pauses during confirmation. CTRL+C returns to BASIC.
Seed movement, merging, closing gaps, and the new seed's appearance are shown in sequence. Wait for the animation to finish before pressing again.
The display shows each cell's number, the highest value, and the number of moves.