It's really not too hard to handle for some things; it can be mentioned in a setting file somewhere. 'We don't plan to have any major advances in technology occur within the game, and any major developments or changes requested will be denied.' (And so on.)
This is one you can even make and keep very vague: 'The game we wish to run has been designed as presented in the news/wiki/whatever, and any major developments or changes that would massively alter the world would change the essential nature of the game as intended, and that everyone on it came here to play. Requests that would fundamentally change the physical, social, or technological landscape and reality of the game will be denied.'
