I think all these casino’s can change their pay out percentages.
Some time ago I saw that the World cup mania payout can be changed, and that’s a MG game.
(I didn’t save the link unfortunately, but I found it through an affiliate newsletter promoting the game. When you clicked it you would end up at the microgaming site – the client version of it I assume – giving more details about the game)
I’m so stupid I didn’t save it, damn!:withstupi