(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 | |
|---|---|---|---|
 | Sudoku Variants Series (276) - Taxi Ride Sudoku by Richard (on 8. July 2020, 00:00) | 76 |  92 % |
| Crossbow (Arrow variant sudoku) by Qodec (on 10. July 2024, 15:34) | 78 | 94 % |
| Anti-Quads 7 by The Bard (on 1. September 2025, 07:40) | 91 | 95 % |
| The 28th Party (CTC Secret Santa 2021) by Niverio (on 29. December 2021, 00:11) | 76 | 97 % |
| Think you can break in? (FOW) by antiknight (on 17. August 2024, 02:06) | 219 | 92 % |
| Squares of Parity Sudoku by Richard (on 21. December 2022, 06:00) | 58 | 95 % |
| Sashigane Whispers by yttrio (on 15. March 2024, 19:40) | 120 | 98 % |
| Kill Or Quads by MSDOS (on 12. July 2024, 08:26) | 67 | 92 % |
| Skyscrapers Sum by abed hawila (on 25. January 2022, 13:00) | 52 | 95 % |
| Hidden Sums by jwsinclair (on 27. November 2021, 20:19) | 37 | 97 % |
| Deflation by jwsinclair (on 13. December 2022, 20:42) | 51 | 95 % |
| Intergrowth (Psycho Look-and-Say/Entropic lines/Modular lines) collab with bellsita by dumediat (on 25. February 2023, 12:51) | 44 | 99 % |
| Stepping Stone Sandwiches by RockyRoer (on 1. April 2024, 18:36) | 40 | 95 % |
| Japanisches Summen by berni (on 4. September 2015, 21:14) | 30 | 98 % |
| Ship's Wheel by Qodec (on 19. February 2022, 11:09) | 64 | 98 % |
| Renban Plasters by antiknight (on 4. April 2024, 18:32) | 38 | 94 % |
| Yin-Yang Whispers by Scruffamudda (on 4. May 2025, 09:46) | 37 | 93 % |
| Skyscraper Tessellation by ChinStrap (on 8. September 2025, 16:30) | 29 | 95 % |
| Peactograph by NicoD (on 18. September 2025, 05:30) | 38 | 98 % |
| Kuromasudoku by Phistomefel (on 26. November 2020, 20:18) | 79 | 99 % |
