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The problem is that sometimes it is extremely difficult to find that visible line between the misguided townspeople and the active Mafia members; this has always been and will always be an integral part of the Mafia itself. And a maniac is something more superficial; he essentially shouldn't care who he executes or who he protects. He is both harmful and useful, and he is both at the same time. At the same time, he makes decisions himself, or, let's say, if he is "bribed" (this word implies many things at once). A maniac should not be useful to the town; he should play for himself.
However, I haven't played the uber-classic Mafia, so I might be wrong about the last point, as the maniac is by default a town member, and I can't deny that he should also help them. However, then the point of playing as him is lost. It turns out that the town will constantly try to lure you to their side, which is not entirely fair, unless the rules of the classic Mafia regarding this issue have undergone significant changes.
In my understanding, the maniac is a complete neutral. Of course, he can listen to requests from both the Mafia and the town, but to the same extent for everyone. Otherwise, it turns out that someone from the opposing sides is playing an additional role, and there is also an extra "killing."
All of the above is, of course, complete nonsense and my IMHO, but I imagine playing as a maniac (in all the numerous branches of the Mafia) in this way. However, due to my modest gaming experience and complete lack of experience playing forum Mafia, I quite allow for the possibility that the maniac is indeed USEFUL to the town. But how will he be useful then, if he specifically eliminates all the townspeople, for example, because he has the right to do so? Or do you have different rules here? Let's say I want to start killing all the active townspeople; I don't think I'll be thanked for it (except perhaps by the Mafia). So, what is the point of such usefulness then? Can't I, as a maniac, kill 100% of the active town and ruin their game, is that forbidden?
I'm waiting for explanations ;)
Sincerely :D