For those that dont know (i dunno if this has been posted already) but you can play as NOD in the demo or set the AI to GDI or try out the different AI types by doing this:
As as you select nod in the drop down menu (its greyed out i know but do it anyways) push the "N" key. Just keep hammering the "N" key and click on nod. Do this with other things except if its setting the AI to GDI push "G" because GDI starts with G and nod starts with N, see? Same rule applies with the different AI types.
Scrin dosent work though you start with 0 units and die after a few seconds.
Also for those that may be interested, theres a major spoiler in the .BIG file. I dont know what it is... i dont want to know.... but somone said there is one, just in case your extra curious or nosey.