I'm going to split the difference between these on the SP vs MP:
When first released, SP is much more important than MP. People will try SP first and if they don't like it they won't even try MP.
However, a game with a thriving MP community has a lot more staying power. Eventually in SP you'll have figured out the best thing to do in every situation against the AI. Humans will continue to come up with new things.
When first released, SP is much more important than MP. People will try SP first and if they don't like it they won't even try MP.
However, a game with a thriving MP community has a lot more staying power. Eventually in SP you'll have figured out the best thing to do in every situation against the AI. Humans will continue to come up with new things.