BODY: Japanese publishers are famously protective of their in-house game technology. So it's genuinely surprising that anyone can now download a piece of Capcom's next-generation engine, free of charge, and ship it in a commercial product.
On October 2, Capcom announced it had open-sourced RE:Dox, its latest data representation and serialization library. The release landed alongside the opening of CAPCOM Open Conference RE:2026, the company's developer-facing event, which kicked off with a talk on the outlook and future of REX — and RE:Dox is described as one of REX's foundational technologies.
Some background: RE ENGINE debuted with Resident Evil 7 biohazard and now powers Monster Hunter Wilds, Pragmata and Onimusha: Way of the Sword. Back in October 2023, Capcom revealed it had begun work on a successor codenamed REX — short for "RE neXt ENGINE" — intended to resolve the pain points that had accumulated in RE ENGINE. Rather than a clean-sheet rewrite, REX is framed as a project to modernize the existing engine in stages.
RE:Dox itself is a token-based structured data engine for .NET. That sounds forbidding, but the repository's README makes it concrete: sample code takes a level-42 character named "Leon" carrying a handgun and a green herb, converts that player data to JSON using RE:Dox classes, then reads it back to rename the character to "Claire" and slip a knife into the inventory. The point is doing that kind of conversion and editing very fast. Capcom's published benchmarks claim parallelized deserialization from JSON runs up to roughly 2.84x faster than .NET's standard System.Text.Json, with the usual caveats about data shape, runtime and CPU.
The library is licensed Apache-2.0, meaning commercial use and modification are both permitted so long as the terms are honored.
The insider take
Capcom's Open Conference series has quietly become one of the most interesting tech-transparency efforts in the Japanese industry — part engineering showcase, part recruiting pitch aimed at a Tokyo and Osaka talent pool that major studios fight over every year. Engine talk in Japan has historically stayed behind closed doors, and engines themselves get judged almost entirely on visuals. Shipping plumbing like RE:Dox on GitHub is a different kind of flex: it tells prospective hires, and rivals, exactly how Capcom thinks about the unglamorous layers of REX.
Originally reported by AUTOMATON (Japanese).