(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 | |
|---|---|---|---|
 | Addition by Subtraction by Cane_Puzzles (on 22. August 2025, 16:57) | 54 |  96 % |
| Reign of Cassiopeia by Tyrgannus (on 24. June 2022, 06:25) | 63 | 95 % |
| Epiphany (Numbered Room and Region Sum Line) by Playmaker6174 (on 30. September 2022, 10:32) | 59 | 97 % |
| Thermometer-Hochhäuser, 8x8 by pirx (on 12. December 2013, 18:08) | 63 | 94 % |
| Triple Decker (Between Sandwich) by tallcat (on 3. August 2022, 17:53) | 66 | 97 % |
| Jubiläumsrätsel - 2 Jahre Rätselportal by Richard (on 1. November 2010, 00:00) | 70 | 94 % |
| Sudoku Variants Series (303) - Assorted Sandwiches Sudoku by Richard (on 13. January 2021, 00:00) | 84 | 98 % |
| Fat X (little killer sudoku) by Aspartagcus (on 9. March 2023, 18:46) | 92 | 95 % |
| Whispering Caves by yttrio (on 28. September 2024, 02:49) | 91 | 99 % |
| Anti-Knight Thermos 3 by Jeet Sampat (on 7. October 2025, 05:57) | 104 | 98 % |
| Rundweg andersrum 3 by Menxar (on 14. September 2009, 10:10) | 48 | 95 % |
| Schlingerpfad 11x17 by adam001 (on 20. September 2012, 13:56) | 18 | 93 % |
| 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 % |
