Digits X-Y-Z in a pill (read top-down or left-right) indicate that the digit Z can be found in row X, column Y.
Each pill crosses two region boundaries (i.e., there are region boundaries between X and Y and between Y and Z), and for each pill, the cell it references must be in a region containing that pill.
Solve online:
F-puzzles.com (turn off conflict highlighting)
Penpa+
CtC App (turn off conflict highlighting)
I wanted to thank the_cogito for helping me figure out the opening and intermediate logic for this puzzle!
Solution code: Column 6, followed by column 7 (18 digits, no spaces).
on 16. February 2022, 20:55 by grkles
Fixing typo
on 16. February 2022, 20:55 by grkles
Added thanks to the_cogito
on 16. February 2022, 00:55 by jmaen
Amazing puzzle, once you get the hang of how the pills are working it solves pretty smoothly indeed! :)
on 14. February 2022, 22:56 by hepcecob
I spent 5 hours staring at this because the rules on CTC do not clarify that each pill has 3 region areas. I interpreted it as each one having exactly 2 regions, not just borders. Please add the same rule clarification to CTC.
Puzzle is great
on 14. February 2022, 01:45 by Piatato
Very elegantly constructed! Felt very smooth. :-D
on 14. February 2022, 00:32 by SudokuExplorer
Lovely idea, and solves very smoothly :-)
on 13. February 2022, 19:42 by Vebby
Great fun! Thanks grkles! :)
on 13. February 2022, 14:31 by Playmaker6174
Very fun and enjoyable puzzle! Quite a couple of sneaky points to spot but all were resolved in a nice way :)
on 13. February 2022, 11:52 by twobear
Very nice indeed! I was expecting the same thing as henrypijames (in the hidden comment) as well :-)
on 13. February 2022, 10:41 by twobear
Thanks, henrypijames!
on 13. February 2022, 10:18 by henrypijames
@twobear: It means that the referenced cell must belong to the same region as (any) one of the three cells in its indexing pill.
Very nice logic, 3½ stars difficulty for me.