EA Maxis has uploaded nearly a dozen game prototypes that were designed to test certain areas of Spore.
Each can be downloaded and played, and range from behavioural and self-propagating star simulators to creature and space-game prototypes. There's even a program that simulates gravitational attraction between particles in clouds.
None of these have been tested for public use, nor are they supported or even explained particularly coherently. The idea was simply to offer eager fans a glimpse behind the evolutionary curtain.
Spore was released last Friday and predictably picked up lots of critical plaudits for the ambitious ideas on offer. Head over to our Spore review to find out why.