Skyscrapers

Einstein Skyscrapers is our hardest level — a 7×7 grid with minimal clues where pure step-by-step deduction is not enough. What sets Einstein apart is that every puzzle requires at least one what-if (contradiction) step: you reach a point where no clue forces the next cell directly, so you assume a height, follow the consequences, and rule it out when it leads to a contradiction. That is genuine critical thinking — and it is still pure logic, never a blind guess.

Our solver verifies each board before publishing: it must be solvable with visibility reasoning, Latin-square elimination, and single-cell what-if analysis — and it must have exactly one solution, confirmed independently by an exhaustive counter. If you stall, the deduction you are missing may be a what-if: pick a stuck cell, test a candidate, and see whether it forces an impossible line.

With so few visible clues, every constraint is precious. Cross-reference opposing clues on rows and columns that share cells, track candidates meticulously with pencil marks, and work methodically rather than fast. Also see the hardest puzzles page for more einstein-level challenges across all puzzle types.