Your game example is limited for viewing to only other developers with 1 game on here... you might be better off if you allow artists to see it.

What sort of workload would this call for? How many variations on backgrounds, characters, buildings, objects, etc?

If it isn't to much of a workload, I could probably work on this with you.

I too must ask about the length of time / number of resources you require... Are you looking for someone to create all new characters, flash component characters from base concepts, or just animation alone?