I got this from twitter. I do not have an Xbox 360, so I cannot confirm it. Let us know if this works for you in the comment section.
To celebrate the launch of #FirstStrike, here’s a free download code. Be the first to redeem it! 6RXTP-TK96Q-WMW94-7W6GC-6X49Z
Here is the link to JD_2020, who is the Community Manager for Treyarch Studio.