(Very) Hard AND nice puzzles
The following list contains portal puzzles that have been rated as nice or very nice and that are difficult. These puzzles are recommended for experts - and allow some time to solve.
| Description | solved | Rating | |
|---|---|---|---|
 | Some Kind of Chaos by marty_sears (on 24. May 2024, 09:25) | 125 |  98 % |
| The Usual Suspects by zetamath (on 22. October 2021, 02:39) | 76 | 98 % |
| Rundweg Family Photo by pokerke (on 14. February 2011, 00:57) | 82 | 100 % |
| Verrätselte Zahlenfolge by berni (on 30. March 2011, 21:27) | 31 | 97 % |
| Negatively Constrained Slingshot Sudoku by stephane.bura (on 6. August 2020, 20:00) | 26 | 93 % |
| Skyscrapers 10x10 by pandiani42 (on 6. August 2020, 12:42) | 26 | 93 % |
| Red and Blue by zetamath (on 19. February 2021, 18:41) | 43 | 96 % |
| Arrow Sudoku by PotatoHead21 (on 26. April 2021, 09:02) | 33 | 90 % |
| Fourteen Arrows by FryTheGuy (on 14. September 2021, 06:47) | 44 | 96 % |
| Pandemonium by Testarossa (on 19. September 2021, 11:11) | 19 | 95 % |
| Suguru Chaos Deconstruction: Anti Equites by crispy16 (on 14. May 2022, 02:25) | 61 | 98 % |
| Stepwell by mormagli (on 14. May 2022, 07:17) | 19 | 95 % |
| Whisper Cave Sudoku by KNT (on 19. May 2022, 08:53) | 75 | 97 % |
| Japanese Sums Nurikabe Arrows (9x9) by Xendari (on 1. January 2023, 08:55) | 15 | 95 % |
| Serpents in the Shadows by XeonRisq (on 13. May 2023, 05:00) | 16 | 91 % |
| Pointed Chaos by yttrio (on 30. June 2023, 20:03) | 102 | 98 % |
| Aquarium Fillomino by wooferzfg (on 4. September 2023, 19:58) | 27 | 100 % |
| Summation U-Bahn Cipher by Agent (on 3. October 2023, 09:00) | 47 | 100 % |
| Biloxi - a Beachcomber Sudoku by glum_hippo (on 23. November 2023, 02:00) | 23 | 98 % |
| The Swamp (Nurikabe Fillomino) by MaizeGator (on 16. July 2024, 16:37) | 41 | 95 % |
