(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 | |
|---|---|---|---|
 | Galaxy Killer Sudoku by Phistomefel (on 11. May 2020, 11:33) | 109 |  96 % |
| Life on 36 cells by Phistomefel (on 13. January 2021, 00:42) | 105 | 95 % |
| Baby Dragon by zetamath (on 18. November 2022, 17:23) | 156 | 96 % |
| Qaak (Quattroquadri/Anti-diagonal/Arrow/Killer) by dumediat (on 24. August 2024, 15:50) | 48 | 95 % |
| Sum Fillomino by AnalyticalNinja (on 10. September 2024, 18:10) | 97 | 98 % |
| Medúlla by mathpesto (on 7. March 2025, 01:05) | 156 | 97 % |
| 1001-Nacht-Rundwege aus Paralleluniversen by ibag (on 4. November 2013, 05:55) | 35 | 99 % |
| Memory Loss by Joseph nehme (on 25. December 2021, 10:45) | 40 | 92 % |
| Coriolis (Lockout X)(Tallcat and Twototenth Collab) by tallcat (on 30. January 2022, 20:56) | 45 | 95 % |
| Dominoes in a fish tank by egubachu (on 23. April 2024, 20:03) | 46 | 91 % |
| Parity Runs #4: Odd Island by Madmahogany (on 12. June 2020, 23:30) | 34 | 93 % |
| Killers in the house by Joseph nehme (on 12. September 2020, 07:56) | 44 | 92 % |
| Highs and Lows by RobK (on 26. March 2021, 18:55) | 36 | 95 % |
| Schrödinger's Killer by starwarigami (on 16. December 2021, 05:20) | 72 | 98 % |
| Hot Box (Killer, Entropy) by Mad-Tyas (on 19. December 2022, 11:46) | 41 | 91 % |
| Chevrons by NicoD (on 16. July 2025, 05:30) | 46 | 91 % |
| Sudoku Variants Series (306) - Square Crow Sudoku by Richard (on 3. February 2021, 00:00) | 68 | 95 % |
| Directions by SudokuExplorer (on 23. December 2021, 00:00) | 96 | 98 % |
| Goldfish - Killer Sudoku by Mr.Menace (on 24. March 2021, 10:14) | 32 | 95 % |
| The Dirty Dozen by twototenth (on 28. June 2022, 08:00) | 56 | 97 % |
