Not much action there coz it is sort of like historical.
Example, if you played the Mordor orks and won on the Palennor Fields out side Minas Tirith, what is the point?
According to the book and the movie, the orks lost, right? So basically it doesn't make sense to play LOTR the outcome is fixed.
You can't play Boromir there also, coz he died in the labyrinth of mine of Moria.
But in 40k or WHF, anything can happen. You can create your own scenario and play your own game.