This excerpt taken from the ATVI 10-Q filed Feb 8, 2006.
No Reverse Engineering. Publisher may utilize and study the design, performance and operation of Xbox 360 or Xbox Live solely for the purposes of developing the Software Title or Online Content. Notwithstanding the foregoing, Publisher shall not, directly or indirectly, reverse engineer or aid or assist in the reverse engineering of all or any part of Xbox 360 or Xbox Live except and only to the extent that such activity is expressly permitted by applicable law notwithstanding this limitation. In the event applicable law grants Publisher the right to reverse engineer the Xbox 360 or Xbox Live notwithstanding this limitation, Publisher shall provide Microsoft with written notice prior to such reverse engineering activity, information regarding Publishers intended method of reverse engineering, its purpose and the legal authority for such activity and shall afford Microsoft a reasonable period of time before initiating such activity in order to evaluate the activity and/or challenge the reverse engineering activity with the appropriate legal authorities. Publisher shallrefrain from such reverse engineering activity until such time as any legal challenge is resolved in Publishers favor. Reverse engineering includes, without limitation, decompiling, disassembly, sniffing, peeling semiconductor components, or otherwise deriving source code. In addition to any other rights and remedies that Microsoft may have under the circumstances, Publisher shall be required in all cases to pay royalties to Microsoft in accordance with and Exhibit 1 with respect to any games or other products that are developed, marketed or distributed by Publisher, and derived in whole or in part from the reverse engineering of Xbox 360, Xbox Live or any Microsoft data, code or other material.