Goal

Sort all nails so every bolt contains nails of exactly one color.

Controls

• Click or tap a bolt to select it — the top nail lifts up
• Click or tap a second bolt to move the nail(s) there
• Consecutive same-color nails on top move together as a group
• A move is valid only if the destination is empty or its top nail matches
• Use Undo to reverse your last move (unlimited undos)

Difficulty

Can I always win from the starting position?

Yes — the puzzle is generated by shuffling a solved state, so it is always solvable.

Is my best score saved?

Yes — your best (fewest moves) is saved per difficulty in your browser's local storage and persists between sessions.

Why can't I move to a bolt?

A destination bolt must either be empty or have a top nail of the same color as the nail you're moving. The bolt also can't be full (4 nails).

Does switching difficulty reset my best score?

No — each difficulty keeps its own independent best score.