(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 | |
|---|---|---|---|
 | Negatively Constrained Slingshot Sudoku by stephane.bura (on 6. August 2020, 20:00) | 27 |  93 % |
| Red and Blue by zetamath (on 19. February 2021, 18:41) | 44 | 96 % |
| Arrow Sudoku by PotatoHead21 (on 26. April 2021, 09:02) | 33 | 90 % |
| Fourteen Arrows by FryTheGuy (on 14. September 2021, 06:47) | 46 | 96 % |
| Pandemonium by Testarossa (on 19. September 2021, 11:11) | 19 | 95 % |
| Suguru Chaos Deconstruction: Anti Equites by crispy16 (on 14. May 2022, 02:25) | 62 | 98 % |
| Serpents in the Shadows by XeonRisq (on 13. May 2023, 05:00) | 16 | 91 % |
| Aquarium Fillomino by wooferzfg (on 4. September 2023, 19:58) | 27 | 100 % |
| Biloxi - a Beachcomber Sudoku by glum_hippo (on 23. November 2023, 02:00) | 23 | 98 % |
| The Swamp (Nurikabe Fillomino) by MaizeGator (on 16. July 2024, 16:37) | 41 | 95 % |
| E : y² + xy = x³ + 12948x + 421776 by aqjhs (on 20. February 2025, 11:36) | 17 | 93 % |
| Nostalgia (Build your own Arrow) by Sartor (on 3. August 2025, 18:29) | 58 | 97 % |
| Chaotic 3D Full Rank by SparkNights (on 23. August 2025, 09:03) | 17 | 98 % |
| Peaceful Destruction by NXTMaster (on 21. November 2025, 00:00) | 21 | 100 % |
| The Ones Who Came Before by Manta-Ray (on 30. October 2025, 14:42) | 17 | 100 % |
| Marco Polo (Loop Deconstruction) by Agent (on 6. June 2023, 09:00) | 100 | 98 % |
| Chaos Construction: Numbered Regions #2 by Jesper (on 2. October 2022, 15:14) | 92 | 100 % |
| Whisper Cave Sudoku by KNT (on 19. May 2022, 08:53) | 77 | 97 % |
| Bafflement by Xenonetix (on 3. October 2022, 01:10) | 59 | 100 % |
| [Fog of War Series] 4. Labyrinth by AstralSky (on 3. November 2022, 15:51) | 56 | 91 % |
