https://www.polygon.com/2018/8/20/17761394/amazon-prime-video-game-pre-order-discount

Amazon Prime’s 20 percent discount on game pre-orders will go away on Aug. 28, the online retailer announced. Instead, Prime members will receive store credit as an incentive to pre-order video games through Amazon, marking a major change to one of the membership’s best benefits.

Only pre-orders of “select video games” will come with the $10 store credit promotion, according to Amazon’s terms and conditions for the offer. Once a customer has pre-ordered a qualifying item, they must wait up to 35 days to receive their $10 via email. That credit will only be valid for 60 days after activation.