Second Son doesn't offer that much replay value, you beat the game twice, that's pretty much it. The side missions also don't offer much of an experience. On the other hand, Ground Zeores offers a ton of replay value, and people still bitched about it being short.
Yes you play it twice which gives it almost double the length ;)
Your point is just a bit petty because there are so many full price games that are shorter than ISS without even any replay value. So why single out this one?
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