(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 | |
|---|---|---|---|
 | Fat X (little killer sudoku) by Aspartagcus (on 9. March 2023, 18:46) | 91 |  95 % |
| Twin chaos sudoku by Richard (on 21. October 2009, 21:48) | 111 | 93 % |
| Schlingerpfad 11x17 by adam001 (on 20. September 2012, 13:56) | 18 | 93 % |
| Thermometer-Hochhäuser, 8x8 by pirx (on 12. December 2013, 18:08) | 62 | 95 % |
| Anti-sudoku puzzle #3 by Nylimb (on 17. February 2020, 06:56) | 36 | 94 % |
| Uncertain Sudoku #8 - Frame or X-Sums by Feadoor (on 27. March 2020, 17:00) | 54 | 96 % |
| Parity Runs #2: Killer by Madmahogany (on 6. June 2020, 14:42) | 42 | 93 % |
| Invisible Slingshot Killers and Silent Killers Sudoku by stephane.bura (on 22. August 2020, 10:44) | 15 | 98 % |
| Sudoku Variants Series (284) - Isolation Killer Sudoku by Richard (on 2. September 2020, 00:00) | 94 | 97 % |
| 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 % |
| Basket Case by cam (on 30. September 2020, 01:34) | 17 | 94 % |
| Prime sum snake sudoku by Nylimb (on 27. November 2020, 07:54) | 20 | 97 % |
| The Negative Diagonal by Lisztes (on 1. December 2020, 01:00) | 16 | 92 % |
| Little Parity Party Sudoku by MagnusJosefsson (on 21. March 2021, 00:32) | 21 | 96 % |
| 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 % |
| Parity Party Renban Sudoku — 'Party Bot' by PixelPlucker (on 31. May 2021, 16:05) | 17 | 95 % |
| Battenburg Killer by MavericksJD (on 12. June 2021, 14:06) | 25 | 95 % |
