(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 | |
|---|---|---|---|
 | Japanische Summen modulo 3 by ibag (on 6. August 2012, 07:46) | 71 |  98 % |
| Dumbstruck by NicoD (on 28. August 2025, 05:30) | 44 | 98 % |
| Madness by jwsinclair (on 12. March 2023, 20:20) | 37 | 96 % |
| 3’s A Charm - Kropki/Arrow Sudoku by Mr.Menace (on 24. July 2023, 20:46) | 43 | 92 % |
| Zipper Sandwich by RockyRoer (on 17. January 2024, 15:23) | 35 | 97 % |
| LM-Qualitraining 2019 (7): U-Bahn unter Hochhäusern by Zzzyxas (on 16. March 2019, 20:19) | 63 | 99 % |
| Krazy Kropki Killer by vidarino (on 19. November 2021, 13:35) | 30 | 93 % |
| 25/12 by starwarigami (on 26. December 2022, 21:15) | 68 | 90 % |
| Reconstructed Frame by XeonRisq (on 23. March 2023, 20:00) | 34 | 93 % |
| A tangled web (Two truths and a lie) by MattYDdraig (on 17. January 2025, 06:23) | 35 | 94 % |
| A Bit of Thermo Fun by ebiggie (on 19. August 2025, 00:08) | 41 | 93 % |
| Four Sum-Linked Sudokus by Genomico (on 10. September 2020, 21:33) | 54 | 97 % |
| Michael Palin by starwarigami (on 4. April 2022, 21:18) | 55 | 97 % |
| Roadmap (Region Sum 159) by tallcat (on 2. December 2022, 15:49) | 88 | 95 % |
| Entanglement by Jay Dyer (on 25. July 2024, 16:15) | 257 | 97 % |
| Entangled-2-Way-Sudoku by Rawcoder (on 11. May 2020, 18:07) | 25 | 94 % |
| Sandwich Sudoku--肉夹馍(2) by cdwg2000 (on 12. November 2020, 07:11) | 26 | 90 % |
| I Chased a Polecat Up a Tree (Inequality Series #5) by twototenth (on 5. October 2021, 08:00) | 29 | 91 % |
| Complete Achromatopsia by angel_shaaark (on 5. June 2022, 10:25) | 36 | 95 % |
| Modulate the Thermostat by FullDeck-Missing (on 26. July 2022, 20:53) | 34 | 92 % |
