(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 | |
|---|---|---|---|
 | Deep Dive Twenty-Five (Killer sudoku) by sujoyku (on 25. October 2025, 14:09) | 128 |  95 % |
| Ringban by Ridhwan (on 1. March 2023, 07:21) | 66 | 91 % |
| Anti-King Thermo Sudoku by Blashyrkh (on 26. January 2024, 16:35) | 64 | 95 % |
| Burrows by jovi_al (on 18. July 2021, 03:38) | 74 | 96 % |
| 2025 Chaotic X-Sums (9x9) by Florian Wortmann (on 25. January 2025, 14:34) | 156 | 97 % |
| Adaptation by mathpesto (on 18. January 2025, 17:49) | 81 | 98 % |
| 010-er Hochhaus mit PS by julius64 (on 24. December 2010, 00:01) | 44 | 90 % |
| Wichtelkalender 2013 - Juli by ibag (on 1. July 2013, 00:00) | 49 | 98 % |
| Table for Four - Easy as Pentomino by uvo (on 19. August 2014, 12:43) | 32 | 92 % |
| 10-in-9 little killer sudoku by Nylimb (on 22. April 2020, 03:31) | 32 | 97 % |
| Stacked Sandwiches Sudoku by stephane.bura (on 8. July 2020, 08:03) | 54 | 95 % |
| Prime Killer Sudoku by udukos (on 25. July 2020, 17:54) | 47 | 95 % |
| Multi-Way Skyscraper Sudoku by SudokuExplorer (on 18. September 2020, 16:00) | 25 | 97 % |
| Unique Aquarium Sudoku by Sam Knott (on 22. September 2020, 15:17) | 55 | 99 % |
| Blackjack Sudoku-It's all 21 by bigger (on 21. January 2021, 21:21) | 24 | 94 % |
| U-Bahn 3 by Dandelo (on 31. January 2021, 18:59) | 42 | 96 % |
| 33 magnificent dots by PetLov (on 31. March 2021, 10:29) | 35 | 99 % |
| Turtle by Arka Badarka (on 15. July 2021, 04:20) | 25 | 93 % |
| Ultraviolet by grkles (on 13. September 2021, 16:33) | 35 | 98 % |
| Killer Knights by Cane_Puzzles (on 29. October 2021, 19:58) | 68 | 97 % |
