(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 | |
|---|---|---|---|
 | Zeta's Nightmare by zetamath (on 15. October 2021, 15:42) | 52 |  97 % |
| Japanese Cave by KNT (on 29. August 2022, 05:29) | 53 | 99 % |
| Leapfrog by jovi_al (on 9. April 2022, 00:30) | 68 | 96 % |
| Birefringence by Jay Dyer (on 25. August 2023, 20:46) | 67 | 96 % |
| Boxed Rooms (Chaos Construction) by thoughtbyte (on 26. August 2023, 13:01) | 64 | 96 % |
| Eine Koralle by matter (on 24. May 2015, 08:51) | 30 | 93 % |
| Puffer Fish by Qodec (on 28. November 2020, 22:05) | 53 | 98 % |
| Nonconsecutive Killer Sudoku by spxtr (on 1. January 2021, 06:21) | 112 | 96 % |
| View Through The Window by SudokuExplorer (on 14. January 2021, 00:01) | 29 | 97 % |
| Wichtel 2020 (3): Wichtel beim Glühwein by wichtel (on 10. April 2021, 00:22) | 23 | 97 % |
| Arrows and Palindromes - II by tenaliraman (on 18. April 2021, 21:22) | 27 | 91 % |
| Questionable Chaos (Y-sums / Skyscrapers sums chaos construction) by Lizzy01 (on 30. May 2022, 11:59) | 21 | 95 % |
| Shadow by TotallyNormalCat (on 4. July 2022, 14:00) | 43 | 98 % |
| Three Kings Go Horse Riding by Scruffamudda (on 15. August 2022, 02:19) | 20 | 93 % |
| Indexed Chaos by Jay Dyer (on 3. September 2022, 23:42) | 85 | 100 % |
| Killer Quads by RockyRoer (on 19. September 2022, 03:14) | 48 | 100 % |
| Anti-Arrow by Eclectic_Hoosier (on 12. October 2022, 06:28) | 16 | 93 % |
| Parasite by XeonRisq (on 10. March 2023, 17:00) | 28 | 93 % |
| Negative Space [Meta-Renban Sudoku] by wisty (on 12. April 2023, 10:41) | 23 | 93 % |
| Despair by XeonRisq (on 3. March 2024, 21:00) | 22 | 98 % |
