I think co-op ruins what could be good single player games but that's just me. Not everything has to be multiplayer.
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And don't get me wrong, co-op has its place in a lot of games, I'm just saying not all games need co-op and Uncharted (or Uncharted: Drake's Fortune at least) is one of those.
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And this could be me just not liking to play co-op in general, but I hate some co-op games you'll be playing (say Gears 2 for instance) and people will always be bothering you to play co-op while you're playing. If I want to play mutliplayer I would go play multiplayer damnit.