one of our members - HALAS organization (Czech Republic) together with sudokucup.com portal has prepared for you a Puzzle competition ABC Test:
http://cs.sudokucup.com/content/abc-test
The competition will be open from 12:00:00 on June 25, 2021 (GMT + 2 hours) to 12:00:00 on June 30, 2021 (GMT + 2 hours)
Please check the Instruction Booklet:
http://sudokualogika.cz/sites/default/files/2021_abc_test_IB_v3_land.pdf
Enjoy solving!