A new white paper by Unity Technologies, the creators of the Unity game engine, shows just how widespread the use of third-party engines for new titles has become.

The paper, released this morning, primarily consists of arguments by Unity on why engines like theirs are beneficial to developers. But the interesting bits are the stories that the report tells about a wide variety of previously pure-custom programming clients — which include Square Enix, Blizzard, and Ubisoft.

Granted, some of the games that used Unity are simpler, graphically speaking, or smaller in scope compared to some of those publishers’ blockbusters. Blizzard Entertainment used Unity for its worldwide card-gaming hit Hearthstone but not for its juggernaut massively multiplayer online RPG World of Warcraft, for example. Ubisoft’s Blue Byte studio used the Unity engine for Assassin’s Creed Identity, a mobile game, but not one of the core titles in the stealth/action-adventure series.

Still, the fact that major developers are using third-party engines for AAA franchises demonstrates a shift in the marketplace away from a time when studios saw custom coding as a bellwether of good or innovative game development. These engines are especially attractive for mobile games, where compatibility changes by the day, and Android OS continues to challenge developers with its many supported devices.

“I think that the main reason that we chose Unity was that the engine has a very powerful animation system, and we were making an animation driven game,” Christian Schell said in the report. He is senior lead programmer on Assassin’s Creed Identity at Ubisoft Blue Byte. “Cross-platform support was also important, and we wanted to support a lot of different platforms.”

Square Enix’s Montreal studio has used the engine for mobile offerings as well, including Hitman Go and Lara Croft Go. Previously, the studio had used nothing but custom coding, but it was also making solely console games rather than mobile releases. Instead of building an engine from scratch, the group elected to use Unity and focus on developing the game, rather than the platform.

“We have a strong creative culture,” Martin Ruel, technical director at Square Enix Montreal, said in the report. “Even when we were making console games, we were using the Unity engine to support our prototyping phase: It was super easy to use, to create behavior, and to integrate assets into our prototypes. Moving to Unity for mobile really helped us focus on crafting compelling experiences instead of spending critical time building engines.”

The white paper was written by Unity, so it naturally shows the company in a favorable light. But the lineup of big name developers who are considering third-party engines like Unity shows the growing role for these engines in newer top-line games, especially for mobile. It’s unlikely that developers will move away from custom coding for their flagship titles, but it’s clear they are betting that selecting plug-and-play engines for smaller titles or uses will make sense in the long run.