In various gaming and online role-playing communities I have seen very young (10-13 years old) and, what's more important, very immature users. If such a user is consistently delivering problems with their immaturity, that user is served a normal problem user treatment according to the rules, but lots of those users are only disruptive for a small part of their time, and then act normally again. They also grow up pretty fast, someone who was a chaotic evil griefer 9 months ago may be a normal person today. But, again, probably not tomorrow.
Outright banning everyone under some age threshold is not an option; it seems unfair to those who do not act stupidly even though they are young at the moment, and there is no real way to check users' age, people may lie.
"Casting" (e.g. checking if someone who wants to enter the community is capable of acting well) prevents some problems, but not all of them: again, someone acting OK today may go on a rage spree tomorrow, honestly regret it 3 days later and go on another rage spree a week after getting unbanned. Casting also takes a lot of time once a gaming community grows big and/or those responsible for casting get a life.
"Treating the users normally" means "speak to them, clean problem stuff left, if they continue to deliver problems, issue a punishment", but the point is that most of the time those kids understand that what they are doing is not good, and don't deliver problems often enough to get a permanent ban. Even if they get banned, the community loses their potentially valuable contribution, even if it means just keeping the community alive. The point is that they cannot always control their emotions.
Pre-moderating their actions is not always an option; it could be used on a forum, but not in a computer game.
So, what can I do to very immature users incapable of controlling their emotions and sometimes going on a rules violation spree and then returning to norm?