(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 | |
|---|---|---|---|
 | Killer Sudoku by Cane_Puzzles (on 8. April 2021, 16:59) | 22 |  91 % |
| Switch by fuxia (on 12. March 2023, 01:13) | 53 | 93 % |
| Prime whispers sudoku (aka "Prime line sudoku") by ibn Muhyiddin (on 4. July 2020, 16:32) | 58 | 96 % |
| Shapes without Shapes by zetamath (on 2. March 2021, 04:28) | 40 | 94 % |
| Renban ModE - Little Killer/Renban sudoku by Mr.Menace (on 29. May 2021, 17:43) | 35 | 97 % |
| Arrow or Centipede? by EricRathbun (on 11. September 2022, 18:08) | 41 | 99 % |
| Stammtisch-Teamrätsel mit Portalen by CJK (on 12. August 2023, 19:08) | 35 | 100 % |
| REN-BAN by zegres (on 17. October 2023, 05:50) | 47 | 95 % |
| Passing Storm (Antiknight Arrows) by Florian Wortmann (on 2. October 2022, 16:19) | 67 | 95 % |
| Little Irregular Killer 2 by Richard (on 29. August 2012, 12:00) | 71 | 95 % |
| Wichtel 2017 (5): Japanische Weihnachtskoralle 2358 by wichtel (on 31. May 2018, 09:05) | 47 | 96 % |
| Little Killers - But which way? by RockyRoer (on 25. August 2020, 22:39) | 45 | 94 % |
| Shy Evens X Odds Sudoku by ICHTUES (on 7. February 2021, 06:00) | 51 | 95 % |
| Wanderlust by 10feet (on 5. August 2021, 13:00) | 28 | 91 % |
| I Chased a Polecat Up a Tree (Inequality Series #5) by twototenth (on 5. October 2021, 08:00) | 27 | 93 % |
| Orange & Blue by FJL (on 4. December 2022, 15:45) | 25 | 91 % |
| Chessmates Sudoku by Genomico (on 30. November 2023, 23:54) | 28 | 91 % |
| Loopy Parity X-Sums by yttrio (on 20. July 2024, 02:56) | 24 | 98 % |
| L.O.V.E. to S.O.L.V.E. by mathpesto (on 2. May 2022, 10:22) | 44 | 94 % |
| Suburbs by Nordy (on 11. November 2023, 11:11) | 36 | 93 % |
