(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 (387) - Adjacent Products Sudoku by Richard (on 5. October 2022, 02:00) | 71 |  93 % |
| Colour Quest by Fenners (on 12. January 2025, 21:02) | 135 | 95 % |
| (+10)-Yang by Kaktuslav (on 30. September 2025, 08:00) | 164 | 96 % |
| High Way by Mujika (on 6. January 2024, 17:47) | 62 | 93 % |
| Numbered Rooms of Entropy by Mad-Tyas (on 6. January 2025, 05:15) | 51 | 92 % |
| Treasury Island by Morisenseiisgod (on 16. May 2025, 18:09) | 52 | 93 % |
| Gossip Circle by mormagli (on 5. June 2022, 23:52) | 44 | 98 % |
| Malfunctioning Modifier Mystery by mnasti2 (on 14. August 2022, 15:01) | 35 | 95 % |
| Sequence Boxes by Cane_Puzzles (on 1. January 2023, 07:48) | 40 | 93 % |
| Pitter Patter by meggen033 (on 8. February 2023, 08:15) | 58 | 94 % |
| Tens(e) Transitions by olima (on 21. May 2024, 10:00) | 42 | 96 % |
| Hunting High and Low (Arrow) by Blashyrkh (on 7. November 2024, 12:15) | 40 | 92 % |
| "Nevermore" ... than Four by XeonRisq (on 13. June 2021, 17:00) | 64 | 94 % |
| Hot Vaulted Banquet by Blobz (on 13. May 2024, 16:00) | 82 | 96 % |
| Pinwheel by etoler (on 7. July 2025, 16:25) | 79 | 91 % |
| Sudoku Variants Series (319) - Star Battle Sandwich by Richard (on 5. May 2021, 00:00) | 95 | 96 % |
| Killeriana: Ein anderer Psycho-Killer by Pyrrhon (on 2. September 2009, 17:39) | 81 | 93 % |
| The 27 Cage Run by AFrayedKnot (on 24. September 2020, 21:12) | 28 | 92 % |
| BetSandwichween by LKegel (on 10. February 2021, 12:32) | 30 | 92 % |
| Killer Knights by Cane_Puzzles (on 29. October 2021, 19:58) | 67 | 97 % |
