(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 | |
|---|---|---|---|
 | Dominoes in a fish tank by egubachu (on 23. April 2024, 20:03) | 46 |  91 % |
| Region Sum Lines Sudoku by Qodec (on 14. January 2022, 20:20) | 124 | 97 % |
| Parity Runs #4: Odd Island by Madmahogany (on 12. June 2020, 23:30) | 34 | 93 % |
| Killers in the house by Joseph nehme (on 12. September 2020, 07:56) | 43 | 92 % |
| Highs and Lows by RobK (on 26. March 2021, 18:55) | 36 | 95 % |
| Schrödinger's Killer by starwarigami (on 16. December 2021, 05:20) | 72 | 98 % |
| Hot Box (Killer, Entropy) by Mad-Tyas (on 19. December 2022, 11:46) | 41 | 91 % |
| new year, who dis? by aqjhs (on 1. January 2025, 00:00) | 44 | 93 % |
| Chevrons by NicoD (on 16. July 2025, 05:30) | 46 | 91 % |
| Renban Caves by yttrio (on 11. January 2025, 02:59) | 138 | 98 % |
| Medúlla by mathpesto (on 7. March 2025, 01:05) | 155 | 97 % |
| Sudoku Variants Series (306) - Square Crow Sudoku by Richard (on 3. February 2021, 00:00) | 68 | 95 % |
| Twin Killer II by Richard (on 25. March 2009, 10:19) | 148 | 95 % |
| Goldfish - Killer Sudoku by Mr.Menace (on 24. March 2021, 10:14) | 32 | 95 % |
| Numbered Sandwich Counts by RockyRoer (on 2. August 2022, 13:57) | 33 | 96 % |
| Lightning Crashes by XeonRisq (on 23. February 2023, 04:00) | 34 | 92 % |
| Careful with that hook, Emmett ! [S-Cell Sudoku] by Christounet (on 1. March 2023, 15:12) | 63 | 95 % |
| Guidance by Jagga (on 1. July 2023, 20:07) | 31 | 93 % |
| Instructionless by dennischen (on 29. July 2023, 04:44) | 28 | 95 % |
| Mystery Boxes by Sumanta(ANU) (on 21. September 2023, 15:45) | 30 | 90 % |
