Not one but 2 prototypes for Spore were released today –  CellCulture and CityMaze.

Cell Culture is a SimCity-like simulation of the spread of life and culture across a planetary surface.

The planet is represented as a grid of cells. Each cell has several variables describing the amount and kind of life present at that location.

Life grows and spreads from cell to cell based on these variables. The more favorable the conditions, the faster the rate of growth and spread.

City Maze is an agent-based city simulation prototype. The player controls a city of sim creatures.

Players may place residential, industrial, entertainment and defense buildings. When sims enter these buildings, they rest, produce income, improve their mood or defend against raider attacks.

Happy, safe, rested sims will multiply and produce income. Miserable, threatened, tired sims will get fed up and leave the city.

You can grab them at the official Spore site!