How do you unlock all the maxis adventures in spore?

Maxis made it so you have to play the original spore to unlock the spore GA's. E.G: Get a warrior Civ to give you a mission, (unless you don't play online) 60% chance that you will get a Maxis Adventure, 35% chance you'll get another Players creation and 5% chance you won't get a GA. The other persons games and the maxis games chances flip when you've already completed the adventure.