How much of a scenario do you ought to know (when you start playing it)?

[Mowgli]

Hm, indeed one way to go about it is to stick to the knowledge that both sides had "historically". The problem is that you never know if this was also the apporach around which the designer has balanced his scenario. 

I don't want to come off as overly competitive. It's just that games in which both players have a chance to win (points-wise - even very asymmetrical scenarios can be balanced) are more exciting to play.