This excerpt taken from the ATVI 10-Q filed Feb 8, 2006.
Entire Agreement; Modification; No Offer. This Agreement (including the Concept, the Non-Disclosure Agreement, the Xbox 360 Publisher Guide, written amendments thereto, and other incorporated documents) and the XDK License constitute the entire agreement between the parties with respect to the subject matter hereof and merges all prior and contemporaneous communications. This Agreement shall not be modified except by a written agreement dated subsequent hereto signed on behalf of Publisher and Microsoft by their duly authorized representatives. Neither this Agreement nor any written or oral statements related hereto constitute an offer, and this Agreement is not legally binding until executed by both parties hereto.
IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed as of the Effective Date on the dates indicated below.