(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 | |
|---|---|---|---|
 | Überlappungssudoku by Richard (on 25. December 2009, 12:00) | 90 |  94 % |
| 3D JapaSumino + 3 by Luigi (on 6. December 2011, 20:25) | 47 | 98 % |
| U-Bahn unter Hochhäusern (Teil 9) by Zzzyxas (on 5. May 2012, 18:21) | 56 | 98 % |
| Die Kryptos - S03E04: Summon by tuace (on 30. October 2018, 10:14) | 50 | 99 % |
| Parity Runs #2: Killer by Madmahogany (on 6. June 2020, 14:42) | 43 | 93 % |
| Slingshot Sudoku - Return of the Invisible Killers by stephane.bura (on 13. August 2020, 20:00) | 16 | 95 % |
| Invisible Slingshot Killers and Silent Killers Sudoku by stephane.bura (on 22. August 2020, 10:44) | 16 | 98 % |
| Even Couples Killer Sudoku by Quarterthru (on 3. September 2020, 12:00) | 25 | 96 % |
| Yajikazu Sudoku by Madmahogany (on 9. September 2020, 14:21) | 49 | 96 % |
| Partial Killer I "Windmühle" by glum_hippo (on 18. September 2020, 18:15) | 84 | 96 % |
| Basket Case by cam (on 30. September 2020, 01:34) | 17 | 94 % |
| Pentominous + Killer Sudoku by mandourin (on 2. October 2020, 23:48) | 16 | 98 % |
| Past Midnight by Selsted (on 20. October 2020, 17:57) | 25 | 94 % |
| Prime sum snake sudoku by Nylimb (on 27. November 2020, 07:54) | 21 | 97 % |
| The Negative Diagonal by Lisztes (on 1. December 2020, 01:00) | 18 | 92 % |
| Ultimate Mashup by Joseph nehme (on 3. April 2021, 09:31) | 37 | 97 % |
| Übungsrätsel LM-Quali 2021: Pentopia-Myopia II by lupo (on 13. April 2021, 20:21) | 22 | 97 % |
| Mystery Kropki Sudoku #2 by Cane_Puzzles (on 13. April 2021, 15:30) | 28 | 93 % |
| Cracked by abed hawila (on 20. April 2021, 01:54) | 13 | 100 % |
| Killer Elephant by SlowLarry (on 25. May 2021, 12:26) | 33 | 93 % |
