(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 | |
|---|---|---|---|
 | Glass Skyscraper Sudoku(P1) by cdwg2000 (on 21. September 2020, 10:20) | 17 |  96 % |
| X-sums Killer Sudoku by udukos (on 4. October 2020, 04:28) | 34 | 97 % |
| KIIIocator: Ultimate Kill by starwarigami (on 11. November 2021, 03:16) | 18 | 91 % |
| Uneven Terrain (Parity Cave Sudoku) by Nordy (on 29. January 2022, 20:15) | 22 | 94 % |
| Lügende Rundwege / Slitherlink Liars by Phistomefel (on 21. March 2022, 12:15) | 33 | 99 % |
| Japanese Sum Battleship Cipher #1 by wisty (on 8. January 2023, 08:27) | 18 | 100 % |
| Pumpkin Wizard by Lizzy01 (on 15. October 2023, 14:09) | 17 | 93 % |
| The Ankheg (Zippular Lines #4) by heliopolix (on 30. December 2023, 16:36) | 19 | 95 % |
| Chaos Sudok-U-Bahn by Christounet (on 21. February 2024, 15:33) | 34 | 98 % |
| Tetris Sum Line by Chad (on 2. March 2024, 00:51) | 29 | 98 % |
| Landvermessung U-Bahn by KNT (on 27. June 2024, 01:47) | 21 | 100 % |
| Blemish [Even Squares, Kropki, Renban] by 3good5you (on 22. December 2024, 17:47) | 21 | 93 % |
| Checkered Grin (Wraparound, Yin Yang) by DubiousMobius (on 16. September 2025, 22:05) | 20 | 98 % |
| Through Space and Time (Chaos Construction) by Agent (on 23. September 2025, 09:00) | 67 | 99 % |
| Chaos Loop by wooferzfg (on 1. December 2022, 05:49) | 44 | 99 % |
| Chaos Sums by wooferzfg (on 28. December 2022, 15:49) | 45 | 98 % |
| Congruity by Andrewsarchus (on 14. December 2025, 03:06) | 49 | 97 % |
| Hochhäuser mit Kellern, Teil 3 by pirx (on 3. July 2015, 18:00) | 35 | 99 % |
| Sagitta (Anti-XV Arrow Sudoku) by Phistomefel (on 1. August 2022, 17:06) | 128 | 94 % |
| Yin Yang Yin by Xenonetix (on 22. January 2023, 22:22) | 40 | 92 % |
