If you finish all levels, you have unlocked most memories. But what is the benefit of unlocking those memories?
1 Answer
Unlocking memories is part of the games storyline and brings extra information into the game. It doesn't do that much and is more a reference to finding and completing every small part of the game like finding a hidden rune or getting full vegetation on a map. There are also achievements to my knowledge to unlock all the memories.
Also there is a FAQ that probably goes into more of it.