A Taxonomy of Game Engines and the Tools that Drive the Industry

The document argues that "game engine" is too vague a term to support rigorous research or clear public discourse, and it proposes a taxonomy that situates engines within the broader game production pipeline. Its central move is to separate product-facing tools, which make up the core engine that ships with a game, from user-facing tools, which the developers and other production roles use to build content. A game engine is defined as the core engine plus these user-facing tools, with the full production pipeline encompassing every connected piece of software. The authors ground this distinction in industry examples, including a costly late switch by Starbreeze from its in-house Valhalla engine, which was essentially a renderer without production tooling, to Unreal, as well as fan confusion over whether Bethesda's engine was outdated during the Fallout 76 controversy.

The empirical groundwork draws on credit-list analysis and platform data. A triple-A title such as Assassin's Creed: Odyssey involved roughly 4,388 credited staff across 55 studios and 692 or more distinct roles by the document's count, a scale that the authors argue no single software product can serve, in contrast to small independent projects like Undertale, built by one main developer and one artist. Engine usage surveys on Itch.io and Steam show Unity dominating Itch.io titles at about 47% and Unreal leading among identified Steam titles at 25.6%, though only roughly 13 to 15 percent of nearly 49,000 Steam entries could be tagged with an engine, leaving the data unreliable and underscoring the need for consistent terminology.

Scope is primarily the commercial digital games industry, with examples drawn from Western triple-A and independent development across the 2010s, referencing sources such as Steam sales data, Itch.io statistics, and GDC 2019 surveys. The paper frames its taxonomy as a foundation for future work, noting open questions such as how an engine's proprietary or open origins shape its included tools and pipeline integrations, and it offers no new quantitative conclusions beyond the figures it surveys.