(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 | |
|---|---|---|---|
 | 5-ABCtje by Richard (on 28. August 2009, 09:01) | 65 |  90 % |
| Der verlorene Schlüssel by berni (on 5. March 2010, 14:34) | 51 | 98 % |
| Alpträume by ibag (on 27. March 2017, 23:55) | 39 | 99 % |
| Machtwechsel in Rätselhausen by Statistica (on 1. December 2018, 18:18) | 30 | 99 % |
| 4 Corners Killer Sudoku by Strosahl (on 30. September 2020, 17:20) | 35 | 94 % |
| Confetti Sums Killer Sudoku by Jesper (on 24. February 2021, 15:10) | 47 | 99 % |
| arROw SudOkU by filuta (on 1. March 2021, 18:08) | 28 | 91 % |
| Invisible Cages by Big Tiger (on 25. March 2021, 10:42) | 27 | 95 % |
| Heterochromia (Killer Sudoku) by emmettcito (on 30. March 2021, 00:42) | 54 | 96 % |
| California skyscraper sudoku by Shinya (on 12. May 2021, 09:02) | 17 | 94 % |
| Thermo Space Force by PotatoHead21 (on 31. May 2021, 03:51) | 43 | 95 % |
| Equal Sudoku by kolot (on 25. October 2021, 07:39) | 26 | 99 % |
| Anti-Knight, Arrows, and Renban by Jeet Sampat (on 26. October 2021, 23:26) | 39 | 94 % |
| Secrets and Lines by starwarigami (on 2. November 2021, 19:23) | 74 | 96 % |
| Killer Ambiguity by abed hawila (on 8. February 2022, 00:34) | 45 | 97 % |
| Progressive Divisors by DiMono (on 3. April 2022, 21:10) | 48 | 96 % |
| Ghost by Jay Dyer (on 13. April 2022, 15:50) | 27 | 97 % |
| Chaos Construction: X-Sums / Sandwich by KNT (on 13. April 2022, 17:12) | 61 | 94 % |
| Imaginary Cages by brandon_bot (on 1. May 2022, 21:14) | 28 | 97 % |
| Full Rank Sandwich by RockyRoer (on 5. June 2022, 03:22) | 55 | 100 % |
