[mockery]

Using GP's definition: "custom" engines -- i.e. engines that are not provided commercially by third parties it's pretty easy to argue Fortnite also uses a "custom" engine. (And that's not pedantry - they obviously have knowledge and access that no licensee could dream of.)

That said, tere are a decent set of AAA games that license Unreal (PUBG, State of Decay, Borderlands series, Arkham series, XCom series) but it's rare among the absolute biggest titles ("AAAA" if you will.)