(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 | |
|---|---|---|---|
 | Chaotic Skyscraper Sums by Florian Wortmann (on 6. August 2022, 16:04) | 89 |  98 % |
| Knapp Daneben Twin Killer Sudoku by Richard (on 24. April 2009, 10:56) | 84 | 94 % |
| Knights Mate by blackjackfitz (on 17. January 2024, 20:52) | 46 | 95 % |
| Blackadder by udukos (on 30. May 2022, 12:14) | 54 | 97 % |
| Colossal Slitherlink Sudoku by Agent (on 5. September 2023, 09:00) | 59 | 99 % |
| Entropy Exhibition by Mad-Tyas (on 19. September 2023, 12:15) | 55 | 93 % |
| Chaos Construction with Slitherlink clues #2 by Phistomefel (on 21. September 2020, 19:41) | 70 | 98 % |
| 4D Arrow Sudoku by FryTheGuy (on 6. July 2021, 11:20) | 16 | 98 % |
| Suguru Chaos Deconstruction #5: Region Sums by mathpesto (on 23. March 2022, 01:51) | 114 | 98 % |
| Ein Geburtstagsgruß von Wachtel, Wechtel, Wochtel und Wuchtel by ibag (on 27. March 2023, 20:00) | 14 | 98 % |
| Chaos Construction: XY-Sums by ns08 (on 28. May 2023, 23:55) | 36 | 94 % |
| BYO Arrows by Celery (on 28. October 2023, 22:44) | 38 | 91 % |
| Build Your Own Nuri-Maze #3: Crossing Slitherlink by Myxo (on 22. February 2024, 14:43) | 21 | 96 % |
| Second Rodeo (collab. with Tallcat) by jwsinclair (on 17. October 2024, 23:06) | 71 | 98 % |
| Bonsai (Ambiguous J-Sum Yin-Yang with Doublers) by MaizeGator (on 19. November 2024, 22:45) | 35 | 100 % |
| Top Right Boi by DubiousMobius (on 21. June 2025, 12:00) | 71 | 100 % |
| Sum Line Sudoku #2 by Phistomefel (on 8. October 2022, 12:57) | 115 | 98 % |
| Adventsportale, Teil 4 by pirx (on 23. December 2018, 12:00) | 47 | 96 % |
| Network by Niverio (on 15. February 2023, 16:20) | 73 | 97 % |
| Shuttle islands [Nurikabe U-Bahn Bridges 13x14] by Christounet (on 16. January 2024, 01:00) | 26 | 96 % |
