(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 | |
|---|---|---|---|
 | Sum Sets by Scruffamudda (on 28. April 2023, 11:09) | 58 |  97 % |
| Anti-Renban Killer by Phistomefel (on 10. March 2020, 13:05) | 82 | 97 % |
| Sudoku Variants Series (307) - Sum Snake Sudoku by Richard (on 10. February 2021, 00:00) | 78 | 96 % |
| Whisper Loop-de-Loop by yttrio (on 25. May 2023, 17:57) | 78 | 98 % |
| Little Killer Sudoku by trivial171 (on 11. May 2020, 00:46) | 53 | 95 % |
| Whodunit by Djmelee3000 (on 11. August 2020, 00:56) | 26 | 95 % |
| 10-in-9 calcudoku #3 (2021) by Nylimb (on 1. January 2021, 00:00) | 25 | 96 % |
| Locked Outside by MavericksJD (on 30. September 2021, 00:00) | 27 | 91 % |
| Ironworks by Bremster (on 20. January 2022, 00:08) | 26 | 96 % |
| Rectangles by Sktx (on 19. February 2022, 13:08) | 23 | 95 % |
| Section 8 by XeonRisq (on 16. June 2022, 01:00) | 30 | 95 % |
| Masyudoku (Masyu/Latin Square/Loop Sums/Ambiguity) by dumediat (on 30. September 2022, 02:35) | 21 | 95 % |
| Hybrid Star Battle Series (014) - Double Back by BenceJoful (on 13. April 2023, 16:17) | 27 | 93 % |
| Jungle Gym by PotatoHead21 (on 28. September 2023, 01:08) | 98 | 96 % |
| Mods, Quads & Odds by ThePedallingPianist (on 15. October 2023, 22:19) | 73 | 98 % |
| Suspension of Disbelief by XeonRisq (on 27. June 2022, 17:00) | 50 | 97 % |
| Black or White Coral by KNT (on 27. May 2024, 03:47) | 45 | 98 % |
| Battle With The Archers 31: When Allies Collide by Playmaker6174 (on 29. April 2022, 22:59) | 68 | 98 % |
| The Suducku King (Thermometer + Renban sudoku) by Aspartagcus (on 1. May 2021, 20:51) | 42 | 94 % |
| Introducing Anchor Sudoku! by FryTheGuy (on 8. June 2021, 16:48) | 25 | 94 % |
