(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 | |
|---|---|---|---|
 | Parity Party XXV, "Gray's Anatomy" by glum_hippo (on 29. December 2022, 03:46) | 21 |  96 % |
| Berlin by zetamath (on 13. March 2023, 04:08) | 27 | 90 % |
| Noobahn by filuta (on 27. May 2023, 18:35) | 10 | 98 % |
| Times Square (CTC Secret Santa 2023) by alexc (on 11. March 2024, 01:34) | 11 | 95 % |
| Zodiac Project: Cluster of Galaxies by Prof.Dori (on 6. November 2024, 00:51) | 40 | 98 % |
| Cavino Wisteria by PrimeWeasel (on 9. November 2024, 09:48) | 26 | 100 % |
| Roller Coaster of Emotions by Agent (on 25. December 2024, 09:00) | 35 | 100 % |
| Sandwich Pseudoku by starwarigami (on 27. January 2025, 06:43) | 11 | 91 % |
| Colossal Cave U-Bahn by Agent (on 29. April 2025, 09:00) | 37 | 100 % |
| Welcome to Chaconopia (Chaos Construction) by Mad-Tyas (on 16. August 2025, 13:24) | 12 | 98 % |
| Wichtels Rätselherbst 2025 (2): Das heiße arktische Klima by wichtel (on 7. October 2025, 20:25) | 10 | 100 % |
 | Bizarro-doku (w/ MathGuy_12) by ThePedallingPianist (on 24. October 2025, 21:24) | 10 | 90 % |
| Arrow/Group Sum Sudoku by ahaupt (on 10. July 2020, 21:53) | 67 | 99 % |
| Sandwich Sudoku by kolot (on 15. July 2021, 18:33) | 36 | 96 % |
| U-Bahn under Tripleblock for polar by KNT (on 1. January 2024, 08:23) | 31 | 97 % |
| Subway To Hell by Piatato (on 27. January 2024, 15:45) | 33 | 100 % |
| Four Alien Theorem (Build Your Own Killer Sudoku) by Agent (on 7. April 2023, 09:00) | 54 | 99 % |
| Wichtel 2012 (1): Der verwirrte Weihnachtsmann by wichtel (on 18. March 2013, 21:30) | 41 | 99 % |
| Misfits by filuta (on 10. November 2022, 17:30) | 40 | 99 % |
| Trail of Prometheus (Secret Satan) by Agent (on 14. January 2025, 09:00) | 20 | 100 % |
