well, as your probably already know, Spore Galactic Adventures is an expansion pack of Spore, so you will need Spore to play this.
in Galactic Adventures, you willl finally be able to beam yourself down on to planets. so, this is kind of recreating the creature stage (which was my favourite, aside form the cell stage), but now you have space weapons, and not only can you fight other creatures, you can create civilizations and help one out. For example, you beam yourself down to a planet , and the mayor needsd your help. now, this is only one of the hundereds of things you can do, but for this mission, you will have to travel the galaxy finding a solution. You will be exploring alot of different planets, and the best part is, other people will be creating planets so you can travel on, and you can too create planets as well! You can even choose the personalitys of the creatures you put on th planets! Their is so much custimization in this expansion pack, its crazy!
though, saying that, we all know Sims. alot of cuztomization their. recreating life on the computer right? well, Sims 3 will be very similar to Sims 2, but their will be alot of little new features, and instead of controlling one person, you will be controlling the lives of several people in a neighbourhood. so, you can get out of the house, intereact with so many different people, and the best part is you are controlling it all. like in Glactic Advetures, you know how you can make all the personalities, clothes, everything.
Really, it all depends. Do you kinda like an actiony feel, and do you want to control aliens? or do you want a more real-life feel, and control humans?
Its all up to that.
How Will You Create The Universe?