Apparently Amazon is adding another benefit to their Prime membership?
You can now save 20% off new physical video games as detailed below and on this page
Prime Exclusive Savings
20% off new physical video games during pre-order through two weeks after release
Discount will be applied automatically at checkout
Offer valid when shipped and sold by Amazon
Video Game Customers Also Enjoy
Release Day Delivery (Free for Prime Members)
Pre-order Price Guarantee
Since I order from there so often anyway this is a really nice bonus!