Rare hasn't really backed up this claim, and it doesn't really matter who thought of what first, in business it's whoever gets their product/idea/concept out their first before rivals.
I like the xbox 360 avatars, but even if Rare did think of it first it looks like they're late to the party since they were released after Nintendo's Miis.
I like the xbox 360 avatars, but even if Rare did think of it first it looks like they're late to the party since they were released after Nintendo's Miis.