There should be sub-stages depicting periodic things in evolution and enlightenment (enlightenment = tribes to space).
Cell should have the normal cell, multicellular small organism, and fish. I want to be a loving fish.
Creature...eh, nuff said.
Tribe should have stone age, medieval age and colonial age.
Civilization should have early 20th century type age and modern day.
Space stage is the sandbox of the game, so nothing there.
Also, there needs to be different ways to start your evolution instead from a dumb geode. How about your a mutated offspring of another cell? Or maybe you were just formed by an omniscient being (Steve :O ).
http://www.gamingbits.com/content/view/4780/2/Another expansion coming to Spore is planned for spring 2009. Straight from EA's announcement: "For the first time, players’ space faring creatures will be able to beam down from their spaceships to explore new planets and earn rewards for completing challenging missions. A new Adventure Creator will allow players to build and share online their own custom missions, providing almost endless gameplay possibilities."