Capcom RE Engine REX Overhaul Brings AI Into Coding and QA Work

The announcement

Capcom has had an unusually strong run. Over the past few years it has shipped hit after hit while many rivals have struggled, and in 2026 alone it released Resident Evil Requiem, Pragmata and Onimusha: Way of the Sword to good reviews and strong sales.1 Now the company has started work on a slower and less glamorous project: rebuilding the in-house tool behind all of those games so that artificial intelligence can work inside it.

On October 2, at its annual technology and recruitment event, Capcom Open Conference RE: 2026, programmer Satoshi Ishida gave a talk called "The Outlook and Future of the REX Project, Further Evolving the RE Engine for the Next Generation."43 REX stands for "RE neXt engine." It is a staged upgrade of the RE Engine, which Capcom first mentioned in 2023.13 Capcom is not building a new engine from scratch. It plans to bolt new components onto the existing one, step by step.4 According to the Japanese outlet GameBiz, whose report most English coverage relied on, Ishida described the end goal as a future in which Capcom "creates games together with AI."17

The RE Engine has been in development since 2014. It debuted with Resident Evil 7 in 2017 and has since powered close to 30 Capcom titles.10 Because it sits under nearly every major Capcom release, including Monster Hunter: World, Street Fighter 6 and Dragon's Dogma 2, any change to it reaches the whole company.8

Three problems behind the plan

Ishida named three pressures. First, games have become so large that even small edits and checks now take a long time, and slow builds hold up iteration.107 Second, more than 2,000 people now use the engine, including overseas staff and developers coming from other engines, so the tools need to be easier to learn and work in several languages.10 Third, he argued that AI has to be built into the development pipeline from the start rather than added later.10

The cost of slow development is easy to see in Capcom's own catalogue. Resident Evil Requiem took about six years to make and was rebooted partway through. Fast Company presents REX as Capcom's response to cycles of that length.5

What REX actually contains

Most of the REX components have little to do with AI on their own. Coverage lists these pieces:

• RE:Dox converts data in many formats into one shared set of rules, which Capcom says speeds up loading and makes editing easier.
• RE:UI is a new framework for internal tools that had become slow, crash-prone and Windows-only. It separates how interface elements look from their state, which also makes automated testing without human oversight easier.
• RE:Log replaces text logs with compact ID numbers. Messages can then be edited without touching code, translated automatically for overseas teams and collected on a central server where anyone can search them.
• RE:Flows is a visual scripting tool that turns designers' gameplay logic into standard code.10
• RE:Runtime processes characters and objects in fixed-size batches instead of one at a time. A separate speed-focused execution layer called RE:C++ sits underneath it.16

Reports do not agree on how many parts there are. PC Gamer and Fast Company describe six programs.15 Kotaku and dlcompare cite five goals and say only two were covered in detail.138 Other outlets list six named systems including RE:C++.16 The likely explanation is that some outlets count RE:C++ as part of RE:Runtime and others count it separately.

The AI connection comes from standardization. GameBiz reported that REX moves the whole engine onto the rules of "the world's most common programming language," which makes it easier for people to use and easier for AI to read.4 One analysis of the published code says the language is C# on .NET. With one consistent codebase, Capcom expects AI that can read the engine's code, write code for it, and run test plays to find bugs.

Open source, with a caveat

Capcom has also released parts of REX publicly, and it says one reason is to give AI systems material to learn from.17 Kotaku and dlcompare report that RE:Dox and RE:Log were both put on GitHub so that AI could eventually understand Capcom's internal code and help catch problems in it.138 A later check found that as of October 7 only RE:Dox was actually in Capcom's GitHub organization. That repository is Apache-2.0 licensed and had passed 1,100 stars. Its README, which no third party has verified, claims parallel deserialization up to roughly 2.8 times faster than Microsoft's standard JSON library.

A Japanese publisher that has guarded its engine for years is now releasing engine code under a permissive license and saying openly that it wants AI models to train on it. That is a notable change in approach.

A translation problem shaped the reaction

Much of the backlash came from one phrase. Early English reports said Capcom wanted to turn the RE Engine into an "AI-generation game engine," which many readers took to mean generative AI producing game content.4 PC Gamer quickly pointed out that the phrase more likely meant an engine for the AI era.1 TheGamer added a note about a possible mistranslation.15 On October 7, Eurogamer issued a formal correction after a Japanese-speaking colleague confirmed that the accurate wording is "towards a game engine for the AI generation."10

The tone of coverage varied widely as a result. Destructoid said Capcom had "ended its string of Ws" and worried that AI would soon create whole programs and replace human playtesters.7 TheGamer said the engine "sadly" seemed headed in a bad direction.15 Kotaku and dlcompare focused on the line Capcom ended the presentation with: "AI is not a replacement for humans."138

Where the stated limits sit

Capcom's position is consistent in one respect. In a shareholder Q&A published in March, it said it would not put AI-generated assets into its games but would actively use AI to improve efficiency in graphics, sound and programming.45 In June it told investors that generative AI was for routine work and that "the creativity at the core of such experiences should be handled by humans."10 Shinichi Inoue, Capcom's VP of game development platform and AI solutions, has described AI as a way to "unleash the potential of creators," not a way to make art.17

The harder question is code. GameBiz's account of the talk describes AI that understands programs and writes them automatically.4 When IGN asked Capcom for comment, a spokesperson said the company has no plans to use generative AI to create its games, and IGN reported that AI will not be used to create assets or programs.3 A slide described by Kotaku points to a narrower role: AI agents play builds, log problems, analyze data, flag visual, gameplay, memory and performance bugs, and propose fixes that a human then applies by hand.13

The most reasonable reading is that both accounts are true at different points in time. Today's REX components are plumbing work. The idea of AI writing code is a long-term goal with no date attached. Capcom has drawn a clear line on shipped assets. Its line on AI-assisted code is less settled. PC Gamer noted that some of the planned tools seem to need AI-generated or AI-assisted code in order to work.1 People should hold Capcom to the asset promise, but they should not read it as a promise about code.

The industry picture

Capcom is not acting alone. In January 2025 it built a prototype with Google that used generative AI to brainstorm environment ideas, for example inventing designs and brand logos for in-game props like televisions.5 The system reportedly used Gemini and Imagen to produce concepts for internal pre-production drafts, not finished content. Take-Two CEO Strauss Zelnick has said his company wants anything that makes work "quicker and cheaper." He added that it has seen no chance to cut staff because of AI, only a chance to stop spending time on low-value tasks.5 Sony talked about machine learning for QA at CEDEC in 2024, which suggests AI-assisted testing has been becoming normal practice for a while.8

Epic and Unity are also adding AI features to Unreal and Unity.6 Capcom has an advantage they do not: it owns its engine and its pipeline, so it can rebuild the codebase around readability for AI instead of selling plug-ins to outside studios. That control is probably what makes a project like REX practical.

The timing is sensitive. Requiem appeared in an Nvidia DLSS 5 demo that drew criticism for AI-enhanced character models, including protagonist Grace Ashcroft.16 Studios are still cutting staff, and Fast Company notes that almost any use of AI is likely to cause tension among developers.5 There is also an obvious irony: Pragmata, a game about the dangers of AI, comes from the same studio.26

What to watch

Capcom has not said when REX components will reach its released games. Resident Evil Veronica, one of the RE Engine projects due next year, may be the first sign of whether the overhaul speeds up production. For now REX is mostly engineering cleanup with an AI goal attached. Capcom's commitments on finished assets are clear, and the open question is how much of the engine's code AI will end up writing.