This is the official demo of Command & Conquer 3: Tiberium Wars.
The demo includes:
While you can normally play only as GDI in the skirmish map, there is a trick that enables you to play as Nod:
Press the key corresponding to the first letter in the side's name or AI Type (N for Nod, R for Rusher) and click on the side/type you're pressing the key for. Then you'll have selected the other sides and AI types to play with!
For example: You want to play as Nod. Hold down N and click on Nod in the side selection drop down. It really works!