Difficulty Levels

Each puzzle is rated both by solver search cost (machine metric) and by human playability (how many steps are forced or ambiguous).

A puzzle may seem “medium” for the algorithm but still feel “hard” for players.

However, when solving online with the built-in helper (instant checks and locked correct rooms), the puzzles may feel easier than the raw difficulty score suggests.

On this site, the displayed ratings reflect this combined view.

1 – Easy

• Quick start with many obvious rooms.
• Plenty of guidance from given numbers.
• Relaxed pace, ideal for learning the rules.

2 – Medium

• Short warm-up, then steady progress.
• Some thinking required, but clues are still helpful.
• Balanced challenge for casual play.

3 – Hard

• Slower start; you may need to try alternatives.
• Fewer easy moves, but breakthroughs come with careful logic.
• Best for experienced solvers.

4 – Expert

• Very little early guidance; few numbers are given.
• Requires planning and spotting subtle connections.
• Challenging even for seasoned players.

5 – Extreme

• Minimal givens and almost no early forced steps.
• Demands patience, hypothesis testing, and deep reasoning.
• For those seeking the toughest challenge.