(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 | |
|---|---|---|---|
 | Mystery Killer Triplets (Little Killer Sudoku) by SudokuExplorer (on 8. August 2020, 03:00) | 21 |  98 % |
| Cage Escape (Thermo Killer) by Stavros96 (on 23. February 2021, 10:44) | 46 | 97 % |
| Speaking to the Atmosphere by EliasKar (on 28. April 2021, 13:28) | 23 | 92 % |
| Quadiagonal by Tyrgannus (on 29. May 2021, 21:19) | 46 | 91 % |
| Little Killer Between Sudoku by SudokuExplorer (on 24. August 2021, 02:00) | 36 | 96 % |
| Thermo x-sums sudoku by Aspartagcus (on 21. January 2022, 08:04) | 23 | 97 % |
| Correspondence by Jay Dyer (on 17. May 2022, 21:46) | 20 | 94 % |
| Caduceus by PjotrV (on 2. June 2022, 13:11) | 57 | 100 % |
| Terminal Velocity by Tyrgannus (on 6. June 2022, 17:31) | 42 | 96 % |
| Bittersweet Candies 2 - A Regular 6x6 Sudoku Pack by Playmaker6174 (on 3. July 2022, 20:07) | 20 | 94 % |
| Jaguar's Paw (irregular 6x6) by Samish (on 23. July 2022, 10:10) | 21 | 95 % |
| The Trident by antiknight (on 12. September 2022, 11:02) | 63 | 95 % |
| Polyamorous Cages by Ennead (on 11. December 2022, 11:24) | 41 | 95 % |
| King's Siege by Sniglett (on 10. March 2024, 23:05) | 43 | 95 % |
| Copycat Blues by Scojo (on 20. July 2024, 06:28) | 20 | 91 % |
| What's in the Box? by lmdemasi (on 22. August 2024, 13:56) | 45 | 96 % |
| In a Kropki Far, Far Away by yttrio (on 12. October 2024, 01:57) | 61 | 94 % |
| Entropy Lockout by Mad-Tyas (on 22. October 2024, 00:01) | 41 | 92 % |
| Celtic Cross by ul-Rhymm (on 12. November 2024, 14:00) | 21 | 90 % |
| Hexaoctoquadri by mathpesto (on 20. March 2025, 16:05) | 44 | 96 % |
