No more 20% off 
Instead you now get a $10 credit. The change starts with orders made on Tuesday, Aug 28th. So if your pre-ordering any game over $50, now is the time to do it.
Here's a copy of the email I just got from Amazon:
We are writing to inform you of upcoming changes to the Prime Savings in Video Games program. Starting on August 28, 2018, Prime members will now get a $10 Amazon promotional credit when pre-ordering select games on Amazon.com. This credit can be used on almost anything sold by Amazon.com. This new pre-order program is replacing the current discount on physical game pre-orders. All eligible pre-orders placed before August 28 will still receive the 20 percent discount under the existing program once the game is released. For more information and restrictions on this new program, click right here.
Prime members continue to benefit from:
• Twitch Prime – free games and in-game loot for Prime members
• Free fast shipping on millions of items including free one-day and same-day delivery in certain areas
• Prime Now – ultra-fast delivery on tens of thousands of items in selected areas
• Prime Video – unlimited streaming of thousands of films and TV shows
• Prime Music – unlimited streaming of a selection of over 2 million songs
• Prime Early access – 30 minute early access to Lightning Deals
• Prime Photos – unlimited photo storage
• Prime Wardrobe – try clothes, shoes, and accessories for free, only getting charged for the items you keep
• Amazon Family – up to 20 percent off diapers and baby food subscriptions
• Prime Reading – unlimited reading on any device with thousands of rotating books, magazines and more
• Household – allows sharing of selected Prime benefits with other members of the household
To learn more about your Prime benefits, click here. To see which of your favorite games are included in the pre-order program, you can always go to www.amazon.com/primevideogames.
Instead you now get a $10 credit. The change starts with orders made on Tuesday, Aug 28th. So if your pre-ordering any game over $50, now is the time to do it.
Here's a copy of the email I just got from Amazon:
We are writing to inform you of upcoming changes to the Prime Savings in Video Games program. Starting on August 28, 2018, Prime members will now get a $10 Amazon promotional credit when pre-ordering select games on Amazon.com. This credit can be used on almost anything sold by Amazon.com. This new pre-order program is replacing the current discount on physical game pre-orders. All eligible pre-orders placed before August 28 will still receive the 20 percent discount under the existing program once the game is released. For more information and restrictions on this new program, click right here.
Prime members continue to benefit from:
• Twitch Prime – free games and in-game loot for Prime members
• Free fast shipping on millions of items including free one-day and same-day delivery in certain areas
• Prime Now – ultra-fast delivery on tens of thousands of items in selected areas
• Prime Video – unlimited streaming of thousands of films and TV shows
• Prime Music – unlimited streaming of a selection of over 2 million songs
• Prime Early access – 30 minute early access to Lightning Deals
• Prime Photos – unlimited photo storage
• Prime Wardrobe – try clothes, shoes, and accessories for free, only getting charged for the items you keep
• Amazon Family – up to 20 percent off diapers and baby food subscriptions
• Prime Reading – unlimited reading on any device with thousands of rotating books, magazines and more
• Household – allows sharing of selected Prime benefits with other members of the household
To learn more about your Prime benefits, click here. To see which of your favorite games are included in the pre-order program, you can always go to www.amazon.com/primevideogames.
