(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 | |
|---|---|---|---|
 | Subway Lines (Chaos Sandwich Sudoku) by Agent (on 15. April 2022, 09:00) | 53 |  98 % |
| Arrows Dilemma by Prof.Dori (on 14. August 2023, 16:02) | 54 | 94 % |
| Toroidal anti-knight sudoku by Shinya (on 1. May 2020, 11:12) | 25 | 91 % |
| 10-in-9 calcudoku #3 (2021) by Nylimb (on 1. January 2021, 00:00) | 25 | 96 % |
| Kite Setting by thoughtbyte (on 22. August 2021, 19:40) | 28 | 96 % |
| Locked Outside by MavericksJD (on 30. September 2021, 00:00) | 29 | 91 % |
| Close Friends II by mathpesto (on 24. December 2021, 07:06) | 28 | 91 % |
| Rectangles by Sktx (on 19. February 2022, 13:08) | 24 | 95 % |
| Section 8 by XeonRisq (on 16. June 2022, 01:00) | 32 | 95 % |
| Snake Nest Sudoku (chaos construction) by Al Fresco (on 9. December 2022, 20:47) | 26 | 96 % |
| EntROPEy by Mad-Tyas (on 2. May 2024, 05:47) | 28 | 95 % |
| Bouncing X-sums by Lizzy01 (on 13. March 2025, 12:58) | 27 | 93 % |
| Dark City (skyscraper cave with fog) by SkepticalMario (on 30. November 2024, 11:11) | 75 | 92 % |
| Twin Killer Sudoku 2008-2009 by Richard (on 1. January 2009, 00:01) | 168 | 93 % |
| Dragon Road by Black_Doom (on 14. July 2025, 17:25) | 67 | 98 % |
| Hinges by jovi_al (on 20. December 2021, 02:37) | 132 | 98 % |
| Pentominous sandwich sudoku by Nylimb (on 28. April 2021, 17:11) | 20 | 97 % |
| Thermal Killer (frei nach Madmahogany) by glum_hippo (on 6. May 2021, 05:30) | 44 | 93 % |
| Introducing Anchor Sudoku! by FryTheGuy (on 8. June 2021, 16:48) | 25 | 94 % |
| Interlocked by Niverio (on 9. May 2022, 22:43) | 71 | 96 % |
