One or All
Place a digit from 1 to 3 into each cell so that each thickly outlined region contains either the same digit in all cells or a different digit in each cell. If two cells are separated by a thick outline, they must contain different digits.
(Rules and example from WPC 2017 IB)
History of the puzzle
Invented by Naoki Inaba (Japan) in 2002 under the name ワンorオール (transliteration of "One or All"). First set of puzzles he created can be seen on his website. 
Appearances in the past WPCs
- WPC 2017/Round 16 by Deb Mohanty