Sudoku competition is the largest Mensa Croatia's project that spans the entire year and in which between 5.000 and 10.000 students (300-500 schools) participate each year.

Mensa Croatia and the „Božidar Vranicki“ Enigmatic Club, in cooperation with the Education and Teacher Training Agency, organize the Sudoku Championship of Croatia for Primary and Secondary Schools. In the largest sudoku competition in these parts, the students compete in three groups based on their age: Brighties (1st to 4th grade of primary school), Cadets (higher grades of primary school) and Juniors (secondary school students).

The Championship was first organized in 2021 for the whole country, as an informal competition that was taking place in Split since 2015 grew larger each year, and it became obvious that there was interest for a sudoku competition outside of the Split-Dalmatia County and among other Croatian counties.