The purpose of the Spy in this game is to cause confusion, as I felt it needed more of that...
The purpose of The Infiltrator was because the Penitent may have been a little over powered, being able to switch teams if the going got tough. So with the Infiltrator, the Church has to be cautious about letting the Penitent in.
Possible win scenarios (Not counting spy):
Village and Vampires
Village and Church
Village
Church
Wolves
Wolves and Vampires
Vampires (I would be extremely surprised if this happened.)
Note that noone in the Church has to be alive to win.
As well, I changed the win conditions of Vampires to include killing all the Church. The normal Vampires cannot kill the Church, requiring them to slander the Church into being lynched. This was intended to give the Infiltrator a reason to kill the Church members.
And the Vampires are still not informed of other Vampires. It is intended to give a sense of individual survival, but there's still a chance of them teaming up.
The whole game is different, as there are several characters that can bring people back, but there can still be suspicions after death. And, there's several conflicts happening at the same time, which all center upon the wolves. If a Doctor brings back a Vampire, it doesn't directly affect him, but it can affect the outcome of the Church conflict.
Speaking of which, the amount of Retributionists and Doctors may vary depending on the amount of people. Doctors/Retributionists are balanced because the Doctor can only bring back someone from the last night, but Retributionists can bring back someone from any time in the game, admittedly for a huge cost.
There's lots of politics in this game. Last Wills and Mayors. Priests and Traitors. And meanwhile the poor village is caught in the middle. But politics is one of the features of the Werewolf game, isn't it?