(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 | |
|---|---|---|---|
 | Sunshine by SudokuExplorer (on 26. January 2021, 02:00) | 39 |  98 % |
| X-Sums / Skyscraper Killer Sudoku by KNT (on 16. September 2022, 18:17) | 53 | 100 % |
| Saturnalia by mathpesto (on 13. January 2024, 05:19) | 60 | 93 % |
| Killomino Sudoku by Phistomefel (on 10. June 2021, 03:54) | 84 | 99 % |
| Little Thermo Killer by Jesper (on 19. June 2020, 23:30) | 51 | 96 % |
| 4-color killer sudoku #1 by Nylimb (on 18. February 2021, 04:42) | 16 | 96 % |
| Stingray (Killer Sudoku) by FryTheGuy (on 13. August 2021, 05:40) | 18 | 95 % |
| Dynamic Duos by Niverio (on 22. August 2021, 17:32) | 46 | 98 % |
| Magic Arrows by PotatoHead21 (on 3. September 2021, 04:34) | 17 | 96 % |
| Chaos Construction: Region Counting by KNT (on 28. April 2022, 17:59) | 49 | 96 % |
| Country Road Fillomino #1 (10x10) by Jesper (on 10. October 2022, 15:41) | 53 | 98 % |
| Peregrine (13x13 Chaos Deconstruction) by Xendari (on 30. April 2023, 16:27) | 37 | 100 % |
| Uncopyrightable Cavino by PrimeWeasel (on 5. September 2024, 22:48) | 16 | 100 % |
| Wanna Take This Outside? by ThePedallingPianist (on 21. December 2023, 01:09) | 73 | 100 % |
| Space Mountain by IcyFruit (on 1. December 2023, 22:12) | 24 | 97 % |
| U-Bahn mit gemischten Hinweisen (Teil 3) by Zzzyxas (on 28. December 2019, 13:32) | 36 | 99 % |
| Genome by Tyrgannus (on 7. July 2021, 21:33) | 37 | 97 % |
| Japanese Sum Cave Cipher #12: Pentominous by KNT (on 26. January 2023, 04:41) | 37 | 99 % |
| Slingshot Fillomino by Jesper (on 15. September 2020, 08:38) | 33 | 98 % |
| Arrowings by kolot (on 25. January 2022, 11:37) | 23 | 97 % |
