(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 | |
|---|---|---|---|
 | Liar Spiral by Niverio (on 29. May 2022, 13:01) | 67 |  97 % |
| Twin Killer Sudoku by Richard (on 23. January 2009, 10:36) | 132 | 95 % |
| Modular Region Sum Lines Sudoku by Phistomefel (on 7. March 2024, 20:52) | 129 | 98 % |
| Switchy by ICHTUES (on 11. December 2022, 06:00) | 64 | 95 % |
| Entropy RSL by Mad-Tyas (on 2. May 2023, 09:02) | 62 | 96 % |
| Infrared [Sum Detector Fillomino] by MicroStudy (on 24. March 2023, 20:45) | 53 | 100 % |
| Kakuro Series 4: Kakuro (Gapped) by Puzzle_Maestro (on 12. May 2020, 13:00) | 56 | 97 % |
| Chaos Construction: Split Killers by XeonRisq (on 14. August 2022, 05:00) | 60 | 95 % |
| Reverb (Killer) by dumediat (on 9. October 2023, 23:11) | 55 | 97 % |
| A Hundred Cells of Chaos by Big Tiger (on 1. August 2023, 01:49) | 53 | 98 % |
| Double Negative by Scruffamudda (on 9. June 2022, 00:32) | 60 | 94 % |
| Not too High, Not too Low by Cane_Puzzles (on 18. March 2023, 19:57) | 53 | 97 % |
| YYSL Whispers by Blobz (on 24. April 2023, 16:00) | 61 | 95 % |
| Zeltplatz im Zauberwald by SilBer (on 21. November 2010, 20:33) | 50 | 96 % |
| Killer Sanduhr by tuace (on 3. November 2013, 04:30) | 46 | 97 % |
| Wichtel 2015 (3): Maschinelle Synthese by wichtel (on 24. March 2016, 10:25) | 47 | 98 % |
| Wichtel 2018 (4): Ein spezielles Weihnachtsmarktgelände by wichtel (on 15. November 2019, 08:12) | 47 | 100 % |
| 10-in-9 sandwich sudoku by Nylimb (on 26. March 2020, 10:16) | 50 | 98 % |
| Mathlements by Qodec (on 7. June 2021, 19:47) | 50 | 99 % |
| Handshake (Arrow Sudoku) by Niverio (on 15. July 2022, 01:08) | 99 | 98 % |
