(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 | |
|---|---|---|---|
 | Known Unknowns (159 killer) by Chilly (on 27. October 2021, 11:12) | 33 |  97 % |
| 6x6 Hypercube by DiMono (on 18. February 2022, 23:40) | 27 | 95 % |
| Prime Party by Realshaggy (on 22. September 2022, 01:17) | 28 | 95 % |
| Sacred Crypt by Allagem (on 6. May 2023, 08:15) | 64 | 95 % |
| Some Things Fogn by pdyxs (on 8. February 2025, 04:53) | 36 | 90 % |
| Sudoku Variants Series (302) - Y-Sums Sudoku by Richard (on 6. January 2021, 00:00) | 88 | 97 % |
| 3 Star Star Battle: Skirmish in the Horsehead Nebula by Thorsby (on 3. September 2020, 00:01) | 48 | 98 % |
| Loop With A Difference by Scruffamudda (on 5. May 2023, 00:09) | 50 | 96 % |
| For A Few Circles More (fillomino) by SkepticalMario (on 31. December 2024, 21:19) | 46 | 95 % |
| Frohe Weihnachten! by Richard (on 23. December 2011, 12:00) | 57 | 95 % |
| Ménage à Trois by Die Hard (on 5. December 2023, 05:16) | 59 | 95 % |
| Tie Those Thermos! by LittleNightmaresLady (on 11. May 2023, 18:38) | 70 | 93 % |
| Trick 17 by Mad-Tyas (on 12. December 2023, 12:12) | 64 | 97 % |
| Milestones by marty_sears (on 5. October 2024, 19:14) | 142 | 98 % |
| Arrow Sudoku by KNT (on 17. April 2022, 05:46) | 94 | 96 % |
| Classic Arrow Sudoku by Phistomefel (on 11. October 2020, 09:48) | 135 | 96 % |
| Rätselwochenende: Table for Four - Paint it Black Tetrominos by uvo (on 26. November 2014, 16:40) | 40 | 93 % |
| Sub-Zero Thermometers by clover (on 20. August 2020, 22:35) | 17 | 98 % |
| Mini Killers by Aspartagcus (on 6. September 2020, 20:30) | 27 | 96 % |
| Odd-Even Sandwich Sudoku by stephane.bura (on 17. September 2020, 20:00) | 16 | 95 % |
