Ok, thanks for that. I'm unavoidably familiar with Lego and Minecraft :)
I agree a lot of children seem to spend a long time making up and changing the rules of their games. Often I think they do so to promote inclusion and increase participation which makes a lot of games more fun, but they also do it to deliberately exclude others. It's intriguing to realise that our adult politics often isn't much more sophisticated than this.
This is a really insightful comment. It is worth taking note of and could be very useful when constructing the game.