Each round, the aim is to count to twelve, following the set rules. In the first round, the only rule in place is that the numbers 7 and 11 are swapped. So you would go around the circle, with each person counting up a number, and in this first round it would go "1, 2, 3, 4, 5, 6, 11, 8, 9, 10, 7, 12". If this is done correctly, then whoever says the number 12 gets to add in a new rule and the counting starts again. E.g. "You must say one and ten backwards". I.e. not only would 7 and 11 be swapped, but you'd now also say "eno" instead of 1 and "net" instead of 10. If at any point someone forgets a rule or gets it wrong, you reset to 1 and they go out. The aim is to be the last person standing (by this point probably with a lot of ridiculous rules!)