I'm giving Worldoku a shot. I'm fairly familiar with country flags, if I may say so myself, as I play Flagle, Worldle and Geozee. And I'm no stranger to Sudoku and Murdoku either. And yet I find this is breaking my brain somehow and I'm struggling a bit to keep the board's state in my head. Maybe I just need more practice.

I do love the concept and I'll try playing more than one assuming I can finish the one I've started. :)