(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 | |
|---|---|---|---|
 | Sackgassen by Myxo (on 15. August 2023, 05:27) | 32 |  96 % |
| Schrödinger 302: Schrödinger's Octopus by ViKingPrime (on 5. May 2024, 11:45) | 30 | 96 % |
| Syzygy by jovi_al (on 13. March 2021, 18:05) | 79 | 98 % |
| Killer Sudoku(002) by cdwg2000 (on 26. August 2020, 08:14) | 25 | 96 % |
| Roman Hieroglyph by lepton (on 17. January 2023, 17:20) | 26 | 96 % |
| Yin Yang Yin by Xenonetix (on 22. January 2023, 22:22) | 38 | 92 % |
| A Narrow Region by PotatoHead21 (on 21. February 2023, 20:25) | 11 | 95 % |
| Reflection by Chad (on 25. July 2023, 18:29) | 24 | 98 % |
| ✚ Whisper-me-Sum-thing Loop ✚ by ElChiglia (on 9. December 2023, 07:15) | 28 | 93 % |
| Chaos Destruction X-Sums by lepton (on 18. February 2024, 08:07) | 29 | 94 % |
| Neodymium (Double Cave Japanese Sums) by Agent (on 4. June 2024, 09:00) | 37 | 99 % |
| Send In The Clones by Jay Dyer (on 25. September 2024, 23:03) | 24 | 91 % |
| Klein's Foggy Glasses by DubiousMobius (on 3. October 2024, 21:43) | 14 | 93 % |
| Chaotic Target Practice by KenGlue (on 11. November 2024, 20:04) | 35 | 98 % |
| Arcade by sfushidahardy (on 17. November 2024, 01:03) | 24 | 96 % |
| Bonsai (Ambiguous J-Sum Yin-Yang with Doublers) by MaizeGator (on 19. November 2024, 22:45) | 23 | 100 % |
| Chaos Deconstruction: Cave by KNT (on 6. July 2022, 07:57) | 73 | 99 % |
| Crypto Crypto Japanese Cave by KNT (on 29. December 2022, 18:27) | 39 | 98 % |
| Colossal Masyu Masyu-Sudoku by Christounet (on 8. October 2023, 21:52) | 38 | 99 % |
| View Through The Window by SudokuExplorer (on 14. January 2021, 00:01) | 27 | 97 % |
