I like FPSs' with freedom but i think that they need limitation because if they didn't it would end getting boring for players if they can wander far away from the battle.

But on that note i bring your attention to a modern game which redefines freedom (in some sense), this game is Medal Of Honer: Airborne. I liked this game because you can land any where on the given map, so there is the freedom, and it has very standard gameplay, shoot advance blow up shoot keep shooting.