@Million: I read an interview recently about the 'enemies' topic, and there won't technically really be enemies, as in obstacles that appear again and again throughout the game that the developers made.
Instead, there are AI patterns that you can apply to things that you make (I'm sure the developers did this to some premade items in-game). For example, if you make a 'scary dinosaur', as long as you put wheels on him, you can assign the 'Chase' AI and it'll chase you throughout the level until you find a way to stop it.
I WANT THIS DAMN GAME!