(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 | |
|---|---|---|---|
 | Islands 4: Chaos Theory by SamuPiano (on 13. March 2024, 20:00) | 15 |  95 % |
| Hunhh? by Joseph nehme (on 7. June 2024, 07:06) | 98 | 95 % |
| Suguru Sandwiches by AnalyticalNinja (on 25. June 2024, 21:25) | 16 | 90 % |
| Renban shifted x-sums by Lizzy01 (on 20. July 2024, 22:55) | 15 | 93 % |
| Set of Shurikens by SamuPiano (on 20. September 2024, 15:44) | 22 | 96 % |
| Computational Maniac by SXH (on 2. January 2025, 04:54) | 21 | 93 % |
| Sigma Grindset by Sniglett (on 24. January 2025, 05:52) | 19 | 91 % |
| Visible Chaos by Belamis (on 12. March 2025, 19:15) | 88 | 96 % |
| The NXT Step to Destruction by Donatello_86 (on 28. December 2025, 09:50) | 16 | 100 % |
| The Minefield by SingingFish (on 12. April 2026, 20:47) | 17 | 91 % |
| Juosan Killer sudoku by udukos (on 25. October 2021, 05:54) | 49 | 96 % |
| Kaboom by mathpesto (on 25. November 2023, 13:51) | 92 | 97 % |
| Überlappungssudoku II by Richard (on 29. January 2010, 12:00) | 73 | 92 % |
| Japanische Bahnhöfe, Teil 1 by pirx (on 27. May 2020, 13:00) | 30 | 94 % |
| Chaos Construction with Slitherlink clues #1 by Phistomefel (on 20. September 2020, 16:25) | 101 | 96 % |
| Parity Party XII, "Herbst" by glum_hippo (on 11. October 2020, 18:05) | 34 | 97 % |
| Kropki'd X-sums sudoku by Nylimb (on 3. November 2020, 02:50) | 32 | 95 % |
| Whispering Arrows by abed hawila (on 9. July 2021, 06:00) | 34 | 95 % |
| Little Killer by PotatoHead21 (on 17. October 2021, 09:59) | 36 | 93 % |
| X-sums Chaos Construction by Lizzy01 (on 14. January 2022, 19:18) | 65 | 99 % |
