were there really 2 big clan alliances fighting each other like in sengoku?
Yes and they were called the "Western Army" and the "Eastern Army".
The fighting was centered around Kyoto with a lot of the clan in the game not really being of any great importance.
The problem is that a game ilke this can't really depict the fighting in one city, other than hard-coding that you only can fight in one specific province, which wouldn't lead to very good or fun gameplay.
the thing i dont like... is that there are 2 alliances here.. and not separate wars...
Eh... separate wars is exactly what we do have. And there are no alliances in the game.