(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 | |
|---|---|---|---|
 | Hammerhead Shark by Lizzy01 (on 18. February 2025, 16:28) | 60 |  92 % |
| Pointing Down by Visumation (on 22. October 2024, 11:56) | 55 | 91 % |
| Sudoku Variants Series (179) - Outside Killer Sudoku by Richard (on 2. May 2017, 00:00) | 108 | 95 % |
| Alien X-Sums Sudoku by Realshaggy (on 11. November 2022, 12:15) | 55 | 92 % |
| Skyscraper, Arrow, and Killer by old thousand (on 3. October 2022, 04:30) | 59 | 92 % |
| 11x11 Classic Star Battle by Phistomefel (on 19. August 2020, 19:31) | 185 | 93 % |
| LM 2023 Überbleibsel - Japanische Summen, schwierigere Version by Zzzyxas (on 8. July 2023, 20:23) | 59 | 96 % |
| One Sum Yin & Yang by Visumation (on 9. June 2025, 10:25) | 81 | 95 % |
| Under Pressure (Pressurized Aquariums) by AnalyticalNinja (on 22. December 2022, 15:00) | 98 | 98 % |
| Archaeology (Nonconsecutive arrow sudoku) by Qodec (on 4. September 2023, 13:45) | 107 | 95 % |
| Chaos Construction: Gaps by KNT (on 29. March 2022, 07:47) | 107 | 92 % |
| So ein Durcheinander by Luigi (on 16. September 2009, 09:42) | 19 | 94 % |
| Crypto Sandwich Sudoku - Easy as ABC by KeyserSoze (on 3. May 2020, 15:52) | 30 | 96 % |
| Wichtel 2019 (8): Notfall in der Wichtelwerkstatt by wichtel (on 23. September 2020, 18:21) | 39 | 98 % |
| 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 % |
| Down The Drain Arrow Sudoku by bram (on 18. September 2020, 21:40) | 44 | 95 % |
| Knightsjump Sudoku by Prutsbeest (on 21. November 2020, 21:29) | 13 | 90 % |
| Sandwich Pseudoku - 10 Donuts by DiMono (on 19. January 2021, 16:47) | 15 | 92 % |
| Distant Relations #1 by Big Tiger (on 25. January 2021, 10:00) | 21 | 94 % |
