(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 | |
|---|---|---|---|
 | Antithesis (Yin Yang Killer Sudoku) by Agent (on 23. August 2022, 09:00) | 211 |  99 % |
| Suburbs by Nordy (on 11. November 2023, 11:11) | 40 | 93 % |
| To infinity... [Toroïdal U-Bahn] by Christounet (on 6. February 2024, 13:51) | 40 | 98 % |
| Bicycle by oskode (on 16. September 2025, 05:57) | 48 | 93 % |
| Stickier Notes by jwsinclair (on 22. January 2026, 15:08) | 80 | 97 % |
| Sums and Products Killer Sudoku by PixelPlucker (on 29. November 2020, 04:46) | 48 | 98 % |
| Kropki XV Puzzle (Oops! No clues!) by RockyRoer (on 5. February 2021, 11:56) | 47 | 95 % |
| OOO OOO by Joseph nehme (on 20. November 2021, 08:07) | 52 | 94 % |
| Sandwich Counts by RockyRoer (on 4. April 2023, 22:21) | 49 | 96 % |
| Irradiated (Thermo, Renban) by Chefofdeath (on 14. May 2023, 20:05) | 54 | 95 % |
| 10 Dots by Mad-Tyas (on 23. December 2024, 01:27) | 51 | 97 % |
| 2. Teil der Trilogie: Ein schwangeres Hitori by berni (on 29. September 2010, 01:23) | 60 | 97 % |
| The Way You Look Tonight by juggler (on 5. June 2024, 06:52) | 65 | 95 % |
| Wichtel 2011 (11): Ein 3D Japasumino by wichtel (on 14. March 2012, 09:00) | 63 | 92 % |
| The Knight and the Knave (Legit/Liar Sudoku) by mathpesto (on 16. August 2022, 23:13) | 80 | 97 % |
| Twin Killer Sudoku VI by Richard (on 29. August 2014, 12:00) | 81 | 95 % |
| Chromosome by ICHTUES (on 16. May 2021, 06:00) | 105 | 96 % |
| Nonconsecutive sandwich killer sudoku by spxtr (on 4. August 2020, 00:53) | 58 | 91 % |
| Cryptic Nurikabe Python by udukos (on 2. January 2021, 16:08) | 16 | 98 % |
| Feeling Left Out by RockyRoer (on 10. February 2021, 11:57) | 18 | 94 % |
