(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 | |
|---|---|---|---|
 | Killer Trainline (Tren + Sudoku Hybrid) by rockratzero (on 28. June 2023, 02:36) | 15 |  96 % |
| Square Dancing by EricRathbun (on 1. October 2024, 10:16) | 23 | 90 % |
| Archaeology (Nonconsecutive arrow sudoku) by Qodec (on 4. September 2023, 13:45) | 100 | 96 % |
| Circle Squared by Ridhwan (on 2. January 2024, 03:27) | 27 | 100 % |
| Trading Places by Kafkapharnaum (on 21. January 2024, 04:54) | 13 | 96 % |
| Heated Sum Loop by yttrio (on 1. March 2024, 21:06) | 38 | 97 % |
| A38 + Enge Höhle (Permakultur) by ibag (on 1. April 2024, 11:44) | 12 | 98 % |
| Loop Compass by Agent (on 9. April 2024, 09:00) | 49 | 100 % |
| Electrostatic Discharge by Allagem (on 14. April 2024, 11:30) | 59 | 93 % |
| Atom by Jobo (on 8. May 2024, 21:34) | 43 | 91 % |
| LM-Qualitraining 2019 (7): U-Bahn unter Hochhäusern by Zzzyxas (on 16. March 2019, 20:19) | 60 | 99 % |
| Pentonimo Kakuro by julius64 (on 4. May 2013, 14:24) | 51 | 96 % |
| Elephants & Castles by juggler (on 1. July 2024, 12:50) | 56 | 97 % |
| Emulsion by FKlauser (on 16. June 2023, 11:11) | 62 | 95 % |
| Hidden X-Sums by jwsinclair (on 4. July 2022, 20:13) | 48 | 98 % |
| Negative Energy by Black_Doom (on 14. July 2024, 07:34) | 46 | 98 % |
| Zippularity by FullDeck-Missing (on 3. August 2024, 06:04) | 42 | 93 % |
| Wichtel 2019 (8): Notfall in der Wichtelwerkstatt by wichtel (on 23. September 2020, 18:21) | 38 | 98 % |
| The Maltese Zipper by Oddlyeven (on 31. December 2023, 16:06) | 41 | 95 % |
| The Way You Look Tonight by juggler (on 5. June 2024, 06:52) | 41 | 95 % |
