In such a movie as Saving Private Ryan, the bunkers where all on top of a cliff. As in any video game, it is the same thing. I would recommend,
Deleting those bunkers, make a big cliff, at least 30 bricks tall, make a little pathway along each side of the bunkers that go up the side of the cliff, make a turret at the top of each pathway, (put some sandbags too for cover) put a german base behind the bunkers at the top of the cliff, and set an event inside of the base so that when the Americans get to it and click on it. It resets the mini game and the Americans won. Also make the shooting hole a little bigger, and put a few turrets so that the players only need a few guns to carry. (Even though it doesn't really matter.) The beach and everything else can stay the same.