(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 | |
|---|---|---|---|
 | Synthesis (Killer/Renban/Antiknight) by dumediat (on 29. June 2023, 00:35) | 77 |  93 % |
| Shadowku by marty_sears (on 12. September 2024, 01:56) | 151 | 97 % |
| Mind the Gap (Arrow X Sudoku) by tallcat (on 28. April 2021, 02:08) | 46 | 94 % |
| No Kings by Merdock (on 31. August 2025, 03:04) | 46 | 95 % |
| Extreme measures (Parity killer/little killer) by sujoyku (on 24. August 2023, 15:00) | 34 | 94 % |
| Gerade-Ungerade-Killer III by Realshaggy (on 17. September 2013, 11:31) | 85 | 95 % |
| Es war einmal eine geheime Schrift by berni (on 1. November 2008, 15:56) | 78 | 92 % |
| Neulich beim Stammtisch Ruhrgebiet by berni (on 15. December 2013, 15:28) | 46 | 97 % |
| Broken Slitherlink by ahaupt (on 21. May 2020, 11:02) | 53 | 99 % |
| Shoot the Pears by tallcat (on 9. April 2021, 15:50) | 49 | 96 % |
| Four Sevens by ThePedallingPianist (on 8. December 2022, 19:53) | 28 | 91 % |
| Circle Squared by Ridhwan (on 2. January 2024, 03:27) | 31 | 96 % |
| Gravitation by Niverio (on 3. July 2024, 19:49) | 25 | 92 % |
| Homebound Sandwich Sudoku by Sebastian Losch (on 25. April 2020, 21:37) | 19 | 94 % |
| Gossiping Queens on 7x7 Torus by SudokuExplorer (on 10. September 2020, 17:44) | 17 | 93 % |
| Sandwich Sudoku--春卷 by cdwg2000 (on 30. October 2020, 13:56) | 18 | 91 % |
| Mystery Sandwiches or X-Sums by UnnamedSorcerer (on 18. November 2020, 01:59) | 15 | 96 % |
| Killer Quiver by MrMercurial (on 4. December 2020, 05:20) | 61 | 91 % |
| Triplet Sums by Realshaggy (on 27. January 2021, 23:59) | 30 | 93 % |
| The BremSter Thermo Conundrum by Zombie Hunter (on 16. September 2021, 00:25) | 19 | 92 % |
