Physics sandboxes have let us play with tossing objects around, particle interactions and launching things across the room. In-game character and model generators let users have fun creating caricatures of ourselves for avatars. So why not have AI sandboxes that let us create weird and wacky AI patterns?
linux.com recently turned me on to N.E.R.O., an interesting title from a university class written with the Torque engine and the open-sourced real-time NeuroEvolution of Augmenting Topologies (rtNEAT) library authored by Kenneth Stanley. If nothing else, it shows why AI can be hard and why current AI in FPS' doesn't seem to "get it" all the time.
Think Moster Rancher meets Creatures and you can kinda get an idea of the attraction. It's definitely in a new "sandbox" genre of its own. It's worth at least 15 minutes of your time... and a free download. The tutorials themselves are worth it.