The Microsoft Store online has the physical disc version of Call of Duty: Infinite Warfare Launch/Standard Edition on sale for $19.99 plus possible tax. Free shipping. Free returns. Free in-store pickup.
Xbox and Windows Store balances and gift cards can be used and redeemed to make purchases on the Microsoft site. They're all the same. I used the free $5 code Xbox recently gave out and Microsoft Store gift cards accumulated from using Microsoft Rewards. This game can be had for free!