I have recently finished putting this map together. Here's a brief outline of the map:
Undead start at the beach and use the wagon to get up the mountain to siege the human village. The humans start out in the inner city and try to repel the undead attack.

Click Here To Download

You have almost made enough maps to make a new crusade

I guess that the cliff map could be the center map then, with prologue being the undead siege level.