Minesweeper

The expert board is 30 columns by 24 rows with 150 mines. That's 720 cells and a mine density just under 21%. The sheer size of the board is the challenge — techniques don't change from hard, but you apply them over a much larger area and for much longer.

Region management matters here more than anywhere else. The board is tall enough that you can't see the whole thing without scrolling on most screens. Work in sections. Clear one frontier fully, mark any ambiguous cells mentally, and move on. Jumping back and forth across 720 cells without a plan is a recipe for missed deductions and accidental clicks.

The remaining mine counter becomes a real tool at this level. With 150 mines to account for, the global count constrains isolated regions in ways that aren't possible on smaller boards. Five hidden cells in a corner with 2 mines showing on the counter? Those constraints often resolve to a unique solution.

Expert boards take time. A clean solve in under 10 minutes is solid. Under 5 is competitive. The world record on a 30×16 (which has fewer cells than this) is under 30 seconds, but that's a different universe of play. Focus on accuracy first. If expert feels comfortable and you want a purer challenge, try Einstein — same techniques, but no guessing allowed anywhere on the board.