RTF is a global modification that replaces all towns in the game.

Well, gnomes would be a good addition; we could keep the bear riders, retain the archers from the elves, and keep the peasants and knights from the humans. Then, we could distribute the creatures differently, like an enhanced 7th-level Ent, an enhanced 6th-level Griffin, and keep the gnomish priests as a 5th-level unit, or enhance the berserkers, upgrading them from 4th to 5th level.