Thank you so much for your interest in the Virtual Villagers games!
We can't say when or if Virtual Villagers 4 and 5 will be available through Steam, but you can always purchase them directly through us (for either Windows or Mac) at these locations:
http://ldw.com/virtual_villagers_4_the_tree_of_life.phphttp://ldw.com/virtual_villagers_5_new_believers.phpWe hope you continue to have fun with your Virtual Villagers!