I have both, but quickly became bored with SH4, I guess I'm just not bothered about the yanks and the japs.
I know you can get the u-boat addon, but I have SH3, so why should I?
My feeling is it was created for the bigger American market, I cannot argue with the GFX, it is much deeper, the underwater world is much more alive, seaweed, boulders et al. Some of the little touches I love, like being able to see the sub through the surface of the water, like a menacing metal shark, kinda spooky.
SH3 for me.
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