Would you believe, I don’t know the criteria or even have a clue what it may be.
It’s all set by head1 the site owner.
Tbh I’ve never asked him

It won’t be something crazy, but it will require a certain amount of contributing obviously, that’s all I can add, sorry.
The rule 33 does state “ undisclosed criteria “ so I wouldn’t expect anything any clearer matey atm.