(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 | |
|---|---|---|---|
 | The Quiet Whispers Between Loops by Jolly Rogers (on 30. September 2024, 20:28) | 45 |  94 % |
| Global Entropea by Scojo (on 12. July 2025, 18:26) | 49 | 97 % |
| The clock by NicoD (on 28. July 2025, 05:30) | 47 | 92 % |
| A Symmetry by twototenth (on 1. November 2022, 08:00) | 81 | 98 % |
| Arctic Expedition by Calesch (on 29. June 2024, 21:38) | 72 | 94 % |
| [Fog of War Series] 22.Caged Snakey by AstralSky (on 13. March 2024, 14:02) | 133 | 96 % |
| Killer Square Sudoku by ProwlingTiger (on 28. April 2020, 04:38) | 30 | 94 % |
| Ouroboros by zetamath (on 20. April 2021, 03:14) | 65 | 97 % |
| Parallel Shots (Arrow Killer Sudoku) by Cane_Puzzles (on 15. August 2021, 17:14) | 31 | 94 % |
| The Spandex Sandwich by PrimeWeasel (on 4. September 2021, 10:09) | 28 | 98 % |
| Square Dance by cristophermoore (on 16. February 2023, 19:24) | 67 | 94 % |
| Galactic Whispers by Knickolas (on 15. July 2023, 10:24) | 60 | 95 % |
| Konferenz der Hellseher (Sudoku) by glum_hippo (on 22. March 2024, 05:05) | 26 | 92 % |
| Ren-Bahn #1 [Renban U-Bahn] by Christounet (on 1. September 2025, 21:12) | 30 | 98 % |
| Bernis Geburtstag - Japanische Summen auf Klein'scher Flasche by ibag (on 15. June 2013, 15:25) | 38 | 93 % |
| Yin-Yang Thermos by Prof.Dori (on 10. October 2023, 17:23) | 47 | 95 % |
| Arrow - Canal View by abed hawila (on 7. January 2022, 13:06) | 54 | 98 % |
| Sudoku Variants Series (371) - Sudoku Hangover by Richard (on 18. May 2022, 01:00) | 62 | 96 % |
| Unplugged by Xenonetix (on 7. August 2022, 02:02) | 56 | 95 % |
| Palenban (Renban+palindrome sudoku) by Qodec (on 11. September 2023, 20:28) | 72 | 93 % |
