(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 | |
|---|---|---|---|
 | Kill-o-meter by Jreg (on 12. January 2023, 07:35) | 13 |  92 % |
| JOKER - Buchstabenrätsel / Letter Puzzle by DocLogic (on 28. April 2023, 14:03) | 30 | 93 % |
| Parity Loop #2: Irregular by Paletron (on 5. September 2023, 11:10) | 14 | 98 % |
| Rätsel Siebenkampf by moss (on 29. September 2016, 22:00) | 38 | 99 % |
| Killer Sandwich by Phistomefel (on 6. February 2020, 22:14) | 90 | 95 % |
| Quintupelblock by ibag (on 17. June 2015, 22:47) | 51 | 97 % |
| pin7guin loves ABCtjes too by ibag (on 6. September 2017, 00:00) | 24 | 92 % |
| Kropki x-sums sudoku by Aspartagcus (on 18. November 2021, 19:45) | 48 | 99 % |
| Armored Harriers by wooferzfg (on 30. April 2023, 06:06) | 26 | 100 % |
| Suguru Chaos Deconstruction #4: Renban + Japanese Sums by mathpesto (on 7. March 2022, 17:30) | 98 | 96 % |
| Roller Coaster mit Extras 12 by Uhu (on 9. March 2019, 22:13) | 39 | 97 % |
| Japanese Sums #2: Balance by Myxo (on 26. April 2023, 21:10) | 37 | 97 % |
| Cave of Loops by Myxo (on 7. December 2022, 11:52) | 48 | 99 % |
| Sudoku Variants Series (310) - Sum Triplets Sudoku by Richard (on 3. March 2021, 00:00) | 64 | 95 % |
| Snake Sweeper Redux by glum_hippo (on 3. August 2020, 13:26) | 11 | 90 % |
| Odd/Even Killer Sudoku (#4) - No given cage totals by Mr.Menace (on 30. November 2020, 22:25) | 13 | 95 % |
| X-Sums (Variant) by cdwg2000 (on 20. March 2021, 09:03) | 13 | 90 % |
| Sum-thing's Wrogn by Jay Dyer (on 5. February 2022, 13:43) | 12 | 100 % |
| Circle of Fifths by Cephalo (on 28. April 2022, 19:40) | 36 | 95 % |
| Nonbinairo by mathpesto (on 28. May 2022, 22:53) | 39 | 98 % |
