What happens when you get to the center of the galaxy in Spore?

Answer 1

Vague answer trying to prevent spoilers: The center of the galaxy contains the Grox empire, who guard the Galactic Core. The Galactic Core is a supermassive black hole that leads to... somewhere... where you meet somebody who gives you something really cool. It's a fun journey, and if you don't want to wait forever to get everything, I recommend cheating. [shift+ctrl+c opens the console, then type help for a list of commands].
A bright, huge gravitational core that-if done correctly, will take you to an alien named Steve. Steve will present you with a gift the staff of life which lets you terraform a planet instantly

Answer 2

You get an achievement and 42 uses for the Staff of Life which turns any planet to T3 instantly. You only get 42 uses because in The Hitchhiker's Guide to the Galaxy the answer to life, the universe, and everything is supposedly 42.

Answer 3

The main thing is the Grox civilization. The Grox are incredibly powerful, almost impossible to befriend, undefeatable, and very aggressive. Almost every star system at the center of the galaxy is populated by Grox. At the very center of the galaxy, the nucleus, is a fun little cutscene featuring the thing that the Grox work so hard to protect. Once you get there and enter the nucleus, the cutscene will play and you will get the Staff of Life, a very powerful tool that will fully terraform a planet in an instant, placing on it all tiers of plants and animals and setting its climate just right. The Staff of Life has a total 49 uses.

Answer 4

You ethier get past THE GROX by beating them or getting past them somehow, or doing some cheat code that makes you have unlimited interstellar travel range.