I have been waiting for it some years too!
I will be out next friday here, I'm going to get it!

Spore is:
You begin as a little 2d cell, you have to eat other little monsters, doing this for some time will make you "level" up. if you "level" up you will be able the add some things to your cell creature; spikes, tails etc. After "levelling" up some times you will be able to go to the creature phase!
When you enter the creature phase, everything will turn into 3D (No its not possible to make an underwater create

) you will be able to make a creature with legs and arms! After doing so, you will have to get a "mate" to lay eggs. You can do this so by building a nice nest! Of course, to stay alive you need to eat other creatures, but watch out! There are creatures that are bigger, faster and stronger than you! After you lay eggs you can further develop your creature. after doing this sometimes you will be able to go to the tribal phase!
When entering tribal phase, you will have a small tribal village! This time you control about 8 creatures. You will have to give them tasks like; fishing, get apples, kill other creatures for meat etc. You can give them clothes for every job too. After getting around 40 creatures (capturing or laying eggs?) you will be able to go to the civilization phase.
When entering civilization phase, you will have over 40 creatures to control in a city. In this city you can change all your buildings to your style or make your own ones! In this phase you can also make vehicles. In this phase its important you get enough $$$. You can do so by trading with other cities and other ways I dont know yet. After buying a space ship you will enter the galactic phase!
In this phase you will be able to go to other planets with your space ship! You can do anything you want to do; shoto a giant laser and kill all those creatures, put a kind of statue on the planet and let them worship you, teleport them in your ship and put them on a planet with no oxygen and see them explode, terraform a planet to your liking etc. You can all do it!
But I have just told what you
can do! there are more things to do in the game! It's surely going to be the best sandbox game ever!