Really? Was Helm's Deep in the middle of a big river? Did it have a huge bridge that spanned a river to get inside the deeping wall? Folks, just because you see siege ladders, orcs, and a big fight in the middle of a rainy night doesn't make the Siege of Cair Andros the battle of Helm's Deep. What a loon.
Yeah, this is for the Lord of the Rings: The Card Game. This is depicting an attack on Cair Andros which is a fortress on an island in the middle of the river Anduin. The defenders are Gondorian soldiers but as you said you can see a couple green-clad heroes there. These are generic heroes leading the battle since, in the game, we can choose 3 heroes from a variety of characters from Middle-Earth. I would highly recommend checking out the game!