(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 | |
|---|---|---|---|
 | Paradigm Shift (S-Cell Japanese Sums Cipher) by Agent (on 7. March 2023, 09:00) | 26 |  98 % |
| Dubai by Jay Dyer (on 7. March 2023, 22:49) | 30 | 93 % |
| Renber Whispan #2 by Sktx (on 8. August 2023, 11:49) | 31 | 96 % |
| 2024 Chaotic X-Sums by Florian Wortmann (on 10. January 2024, 19:23) | 102 | 98 % |
| Killer Sudoku - The Knot by Phistomefel (on 31. August 2020, 23:10) | 85 | 98 % |
| Palindrome Madness by SirWoezel (on 2. June 2020, 18:26) | 22 | 93 % |
| Bullseye Sudoku by RockyRoer (on 29. July 2020, 21:59) | 48 | 99 % |
| Even knights fear arrows by Phistomefel (on 19. November 2020, 19:09) | 88 | 96 % |
| Regional Yajilin — 'Abandoned Factory' by PixelPlucker (on 17. January 2022, 06:43) | 20 | 99 % |
| Double Agent by DadJokes (on 29. September 2022, 21:48) | 21 | 97 % |
| Haisudoku Thermoline (Thermo Sudoku+Haisu hybrid) by AnalyticalNinja (on 15. November 2022, 03:02) | 20 | 100 % |
| Silent Suguru by dennischen (on 27. April 2023, 01:12) | 43 | 99 % |
| JCQ #5: Fawlty Towers (Liar Thermo Killer Sudoku) by peterchayward (on 17. July 2020, 11:13) | 40 | 97 % |
| Stitch the Broken Ring by LuckyNumber8 (on 13. April 2021, 01:43) | 17 | 92 % |
| Ambiguous Entropy by XeonRisq (on 28. December 2022, 23:00) | 145 | 98 % |
| Hybrid Star Battle Series (017) - Easy as ABC by BenceJoful (on 6. May 2023, 01:45) | 16 | 96 % |
| Is 4 a Low Digit? by blackjackfitz (on 30. August 2023, 03:23) | 20 | 90 % |
| Inequalities by Ennead (on 31. October 2023, 11:53) | 15 | 98 % |
| Lacunae (Sortadoku/Sandwich/Projected Sums) by dumediat (on 26. November 2023, 16:29) | 48 | 96 % |
| Building Regions in Fog of War: Border Patrol 2 by Jeet Sampat (on 7. April 2024, 12:24) | 18 | 90 % |
