(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 | |
|---|---|---|---|
 | Quantum-safe sudoku by chameleon (on 26. September 2022, 20:11) | 31 |  91 % |
| The Unity of Opposites by ViKingPrime (on 19. May 2024, 00:45) | 34 | 91 % |
| Shade Your Own Puzzle: YinYang vs Sudoku #1 by Playmaker6174 (on 20. August 2024, 19:00) | 61 | 96 % |
| Verspäteter Geburtstagsgruß aus dem All by ibag (on 27. June 2019, 00:00) | 29 | 99 % |
| Little Killer Arrow Sudoku by Phistomefel (on 2. March 2021, 11:50) | 72 | 97 % |
| Aim for the Sky by udukos (on 28. March 2021, 22:12) | 33 | 98 % |
| Supernova by Nahileon (on 3. November 2021, 20:32) | 73 | 99 % |
| Chaos Construction: X-Sums with Doublers by KNT (on 30. August 2022, 22:01) | 71 | 97 % |
| Dancing Like Butterfly Wings by dennischen (on 31. December 2024, 02:28) | 47 | 96 % |
| Syzygy by jovi_al (on 13. March 2021, 18:05) | 85 | 98 % |
| Philadelphia by ICHTUES (on 28. November 2021, 06:00) | 46 | 95 % |
| Kodama by zetamath (on 20. January 2022, 04:32) | 44 | 98 % |
| Chaos Construction: Oenopion's Revenge by Niverio (on 3. July 2022, 10:13) | 82 | 99 % |
| Chaos CaveSudoku by MagnusJosefsson (on 7. December 2022, 11:55) | 83 | 98 % |
| Shading Sudoku Collection by KNT (on 10. August 2022, 05:09) | 42 | 97 % |
| Matty Didn't Call You Back Because He Had The Wrogn Number by Laake (on 26. September 2024, 22:11) | 90 | 96 % |
| Japanische Inseln, knapp daneben by pirx (on 19. October 2014, 17:30) | 50 | 99 % |
| Roller Coaster mit Extras 13 by Uhu (on 21. March 2019, 22:34) | 51 | 99 % |
| Chaos II: The Two Killers by lerroyy (on 18. April 2022, 22:25) | 51 | 98 % |
| X-Sums killer sudoku #2 by udukos (on 10. October 2022, 21:08) | 60 | 98 % |
