(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 | |
|---|---|---|---|
 | Ten - Qodec Collab by the_cogito (on 6. May 2022, 19:39) | 43 |  94 % |
| Sub Zero Nabner by gdc (on 27. September 2023, 13:05) | 47 | 96 % |
| Chaos Construction: X-Sums and Lines by KNT (on 2. April 2022, 19:42) | 83 | 98 % |
| Falling Arrows by antiknight (on 24. December 2022, 02:44) | 81 | 94 % |
| Killer Square Sudoku by ProwlingTiger (on 28. April 2020, 04:38) | 29 | 94 % |
| Japanische Bahnhöfe, Teil 1 by pirx (on 27. May 2020, 13:00) | 28 | 95 % |
| Ouroboros by zetamath (on 20. April 2021, 03:14) | 62 | 97 % |
| The Spandex Sandwich by PrimeWeasel (on 4. September 2021, 10:09) | 28 | 98 % |
| Poisson Ratio by cam (on 23. December 2022, 21:35) | 31 | 94 % |
| Negator XS by thoughtbyte (on 13. September 2023, 00:55) | 65 | 97 % |
| Sight Lines Sum (Yin Yang) by palpot (on 15. May 2024, 21:00) | 35 | 95 % |
| Tatamidoku by mathpesto (on 21. June 2023, 04:41) | 86 | 97 % |
| Arctic Expedition by Calesch (on 29. June 2024, 21:38) | 71 | 94 % |
| Horseshoes and Handgrenades by purpl (on 15. September 2021, 17:23) | 45 | 98 % |
| Slitherlink Cave Sudoku by RockyRoer (on 16. August 2023, 14:05) | 58 | 97 % |
| Cobra's Curse by IcyFruit (on 1. February 2024, 14:37) | 77 | 97 % |
| Four Corners (Arrow Killer X) by tallcat (on 13. May 2021, 15:02) | 88 | 99 % |
| Parity Little Killer Sudoku by Aspartagcus (on 16. July 2020, 23:04) | 15 | 94 % |
| Snakes Sandwiches & Chaos by emmettcito (on 8. August 2020, 04:39) | 16 | 98 % |
| Rings Around The Rosy Sudoku by RockyRoer (on 12. August 2020, 16:59) | 46 | 96 % |
