(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 | |
|---|---|---|---|
 | Uneven Terrain (Parity Cave Sudoku) by Nordy (on 29. January 2022, 20:15) | 19 |  93 % |
| Fünf aßen Neun by MavericksJD (on 30. January 2022, 19:53) | 26 | 95 % |
| Chaos Construction: Color Mixing by KNT (on 15. May 2022, 17:41) | 36 | 97 % |
| Deep sea weirdity (Between lines sudoku) by Lizzy01 (on 15. June 2022, 22:38) | 24 | 97 % |
| Chaos Construction: Oenopion's Revenge by Niverio (on 3. July 2022, 10:13) | 79 | 99 % |
| Three Kings Go Horse Riding by Scruffamudda (on 15. August 2022, 02:19) | 15 | 92 % |
| Quantum-safe sudoku by chameleon (on 26. September 2022, 20:11) | 30 | 92 % |
| X-Sums killer sudoku #2 by udukos (on 10. October 2022, 21:08) | 58 | 98 % |
| Yin Yang Yung by Big Tiger (on 5. December 2022, 23:52) | 16 | 100 % |
| Japanese Sum Battleship Cipher #1 by wisty (on 8. January 2023, 08:27) | 14 | 100 % |
| Prison Party of Eight by lepton (on 10. January 2023, 18:59) | 18 | 93 % |
| Tachyons and Black Holes (Black Hole) by heliopolix (on 16. January 2023, 20:00) | 33 | 95 % |
| Nurikabe and Chaos by wooferzfg (on 20. February 2023, 02:53) | 63 | 100 % |
| Field Lines by mathpesto (on 8. April 2023, 21:10) | 95 | 98 % |
| O'Position [Ciphered Position Sums Fillomino] by Christounet (on 30. April 2023, 22:51) | 22 | 99 % |
| Thinking in Circles by Mennoo_ (on 22. June 2023, 11:34) | 23 | 93 % |
| Ancient Tablet by Kafkapharnaum (on 25. July 2023, 15:51) | 23 | 100 % |
| Desert Deity by DadJokes (on 1. December 2023, 19:43) | 35 | 95 % |
| Chaos Sudok-U-Bahn by Christounet (on 21. February 2024, 15:33) | 28 | 98 % |
| In Chaos there is Order by Ali M (on 15. March 2024, 21:55) | 29 | 92 % |
