Whoa!  Among all of the prototypes released so far, the two for this week are the best!  The two Maxis put out are called Space and SPUG.

SPUG

SPUG is a tunable gameplay prototype for the Creature level of Spore.

The player controls an avatar creature on a simple planetary terrain where they may hunt prey, evade predators, eat, rest and level up their stats.

No limitations are placed on leveling up or cheating stats. This tool was intended to give designers the opportunity to explore different economies for the creature game, so limitations on power ups and level ups are self-imposed.

Space

‘Space’ is a gameplay prototype of the Space level of Spore.

The player explores a galaxy of stars with a spacecraft, discovering new worlds to terraform and colonize and encountering alien species to fight or befriend.

Successful colonies provide the player with resources and income which they can invest in technological research. Advanced technologies allow the player to terraform, colonize fight and explore more effectively.

These two great prototypes can be found at the official Spore site.