From the release:
Imperial commanders and Rebel strike team leaders, gather your soldiers and prepare for tactical Star Wars™ combat. Imperial Assault is now available at your local retailer!
You’ll have twice the opportunities to immerse yourself in the Star Wars universe with the two complete games included in Imperial Assault. In the campaign game, up to four players command heroes of the Rebellion, battling against a single Imperial player in a narrative campaign that changes every time you play through it. The skirmish game, on the other hand, gives you the chance to go head-to-head with a single opponent – mustering your own armies and fighting to complete conflicting objectives. Whichever game you play, your tactical decisions decide the fate of the galaxy!