While not officially announced by Amazon, it is definitely is happening where Prime members seem to be getting discounts on quite a few games and mainly popular ones at that like Batman: Arkham Knight and several preorders for AAA games for about $5-$10 USD off in total.
The only real indication if a game is qualified for this discount is if it has a text box including the below, and even then the discount is seemingly random for the most part and you can only see it in your cart.
“Members of Amazon Prime qualify for a lower price on this item when shipped and sold by Amazon.”
Realistically though this makes Amazon Prime a real option now for gamers who happen to preorder (and also shop on Amazon a lot too) a lot according to the below list of from what is known of all current games with this discount you could end up saving easily enough to pay for the slightly high price of the normal Amazon Prime membership if you end up just ordering many of the “must have” AAA titles on preorder currently as those seem to have the highest discounts as well.
Super Smash Bros. (3DS) — $34.99 ($4.97 off)
Elder Scrolls Online: Tamriel Unlimited (PS4, Xbox One) — $49.99 ($8.52 off)
Splatoon (Wii U) — $52.99 ($6.97 off)
Batman: Arkham Knight (PS4, Xbox One) — $49.99 ($9.97 off)
Tom Clancy’s The Division (PS4, Xbox One) — $52.99 ($6.97 off)
Tom Clancy’s Rainbow Six Siege (PS4, Xbox One) — $52.99 ($6.97 off)
Kirby & The Rainbow Curse (Wii U) — $34.99 ($3.39 off)
The Legend of Zelda: Majora’s Mask 3D (3DS) — $32.99 ($3.26 off)
Puzzle & Dragons Z + Puzzle & Dragons Super Mario Bros. (3DS) — $26.99 ($2.97 off)
Lego Jurassic World (Xbox One) — $52.99 ($2.69 off)
Madden NFL 16 (PS4, Xbox One) — $54.99 ($4.97 off)
Halo 5: Guardians (Xbox One) — $52.99 ($7.00 off)
F1 2015 (PS4, Xbox One) — $52.99 ($6.97 off)
Call of Duty: Black Ops III (PS4, Xbox One) — $49.99 ($10.00 off)
Star Wars Battlefront (PS4, Xbox One) — $54.99 ($4.97 off)
Star Wars Battlefront Deluxe Edition (PS4, Xbox One) — $62.99 ($7.00 off)
Final Fantasy XIV: Heavensward (PS4) — $34.99 ($4.97 off)
Rory McIlroy PGA Tour (PS4, Xbox One) — $49.99 ($9.97 off)
Guitar Hero Live bundle (PS3, PS4, Xbox 360, Xbox One) — $89.99 ($10.00 off)
Mario Kart 8 (Wii U) — $52.99 ($6.31 off)
DualShock 4 PlayStation 4 controller — $44.99
Mario Party 10 (Wii U) — $44.99 ($1.79 off)
Minecraft (PS4, Xbox One) — $17.99 ($1.50 off)
