(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 | |
|---|---|---|---|
 | Odd Couples Killer Sudoku by Quarterthru (on 29. August 2020, 12:00) | 45 |  95 % |
| Wrogn Answers Only by jwsinclair (on 19. October 2022, 19:44) | 191 | 98 % |
| Chinese Takeaway (Yin Yang Killer) by BenTen (on 3. May 2023, 23:51) | 140 | 97 % |
| Chaos Construction: Gaps by KNT (on 29. March 2022, 07:47) | 102 | 93 % |
| Alien X-Sums Sudoku by Realshaggy (on 11. November 2022, 12:15) | 54 | 92 % |
| Warp Speed by The Bard (on 16. October 2024, 00:02) | 123 | 96 % |
| Skyscraper, Arrow, and Killer by old thousand (on 3. October 2022, 04:30) | 58 | 92 % |
| Sudoku Variants Series (279) - Parity Sections Sudoku by Richard (on 29. July 2020, 00:00) | 65 | 98 % |
| In Line by jwsinclair (on 14. August 2024, 17:45) | 59 | 95 % |
| Mystery Box by Jolly Rogers (on 18. October 2023, 11:57) | 65 | 97 % |
| Sudoku Variants Series (179) - Outside Killer Sudoku by Richard (on 2. May 2017, 00:00) | 98 | 95 % |
| Combi Windoku by Richard (on 23. July 2009, 09:57) | 112 | 91 % |
| So ein Durcheinander by Luigi (on 16. September 2009, 09:42) | 19 | 94 % |
| Ameisenstrasse by Luigi (on 6. May 2011, 12:16) | 21 | 93 % |
| ROCK STAR - Buchstabenrätsel by DocLogic (on 5. February 2020, 19:28) | 37 | 91 % |
| Parity Party II - "Little Killer at Summer Camp" by glum_hippo (on 11. April 2020, 20:54) | 45 | 92 % |
| Crypto Sandwich Sudoku - Easy as ABC by KeyserSoze (on 3. May 2020, 15:52) | 30 | 96 % |
| Hidden X-Sums & Sandwiches by BL00DW0LF (on 7. August 2020, 05:39) | 28 | 93 % |
| Spiral Galaxies / Bent Hashi by stefliew (on 23. August 2020, 18:20) | 16 | 94 % |
| Anti-Killer Sudoku #3 by JoJoMcFroYo (on 16. September 2020, 22:49) | 22 | 96 % |
