Mensa Absolutely Nasty Sudoku Level 5 - Mensa Author:Frank Longo This is it—puzzles so amazing that they’ll make your brain explode! Only the best of the best need apply to work through such skills as: Jellyfish; One-Sided Gordonian Polygon; Multi-Digit One-Sided Gordonian Rectangle; and Turbot Fish. Plus, in this case, they’re used in combination to create the ultimate test.