Capcom Builds an AI-Era Engine and Leaves the Art Human

On October 2 in Tokyo, Capcom programmer Satoshi Ishida said REX will push RE Engine into the AI era without replacing it. He did not announce a machine that will paint Resident Evil. He described a staged rebuild so people and models can share the same tools.

English write-ups of that talk reached for “AI-generation game engine,” a phrase that sounds like generative art. The Japanese target Ishida named is an AI-era engine (AI世代), built so code, logs, and tests can be read by staff and by models. Capcom’s live gift that morning was a data library on GitHub, not a new way to fill a disc.

The Japanese Line Was an AI-Era Engine

Ishida spoke in the opening slot of the professional day at Capcom Open Conference RE 2026 talks, a house tech event that also runs student sessions in Tokyo and Osaka. His session title framed REX as the outlook for taking RE Engine into the next generation. The long-term line attached to that work is a future where Capcom “creates games together with AI.”

Create games together with AI.

Satoshi Ishida, programmer, Capcom Open Conference RE 2026

Read next to the rest of the hour, that slogan is about the factory, not the finished monster. Ishida said REX unifies the stack on the rules of a widely used programming language so humans can write it and models can parse it. Down the road, he said, a model could write programs and run test plays to hunt bugs. He also said Capcom is putting some of that plumbing on the public internet so other people can use it to train models.

The English calque “AI-generation” does a job the Japanese did not. 世代 here is the same “generation” you hear in next-generation hardware, an era, not a prompt that emits a zombie. People who only saw the English line heard slop coming to Street Fighter. The talk was about making the engine legible.

Three Scale Problems Sit Inside RE Engine

Capcom started RE Engine in 2014 and first shipped a game on it in 2017 with Resident Evil 7. More than eight years on, Ishida said the same core now carries more than 27 Capcom titles and has hit three walls that a from-scratch rewrite would not fix fast enough. REX is the name for the bundle of named systems meant to raise that core in place.

THE THREE BOTTLENECKS ISHIDA NAMED

• Game size: Modern titles hold so much data that a small tweak and a playtest now stall, and iteration speed has fallen as asset counts and game code have grown to several times the 2017 load.
• Who logs in: Almost every Capcom developer sits on this engine, including overseas staff and people who arrived from other engines, so the tools have to be easy and usable in more than one language.
• AI in the workflow: Wiring AI into development, including agents that can test and handle QA with more freedom, is now a required condition for keeping future work moving, not a side experiment.

Capcom’s own preview of the talk put the headcount in plain numbers: the engine now has more than 2,000 active engine users. That is why Ishida’s pitch spent as much time on frozen editors and unread logs as it did on models. An engine that only a small tools team can operate will not absorb another hiring wave, and it will not host an agent that has to click the same panels a designer clicks.

What REX Adds Without a New Engine

REX is short for RE neXt ENGINE. Capcom is not throwing out RE Engine. It is grafting on pieces tagged RE: and lifting the current engine in stages, a path the company already sketched in 2023 when it showed an eight-part slide. On October 2, Ishida walked through five of those pieces as working systems, not a new brand on the box.

REX SYSTEMS ISHIDA WALKED THROUGH

The older 2023 slide also named REAssetStream, REProfiler, and RELauncher. Those did not get the same walkthrough in the October talk, and Capcom has not given a public ship date for any of the layers as a player-facing engine bump.

Editors That Can Be Tested With the Screen Off

RE:UI is the most human of the five. Ishida said Capcom’s old editor stack, built on common industry kit, now freezes because the screens are huge, pauses when garbage collection runs, and takes too much code to change. Those tools also stayed on Windows. RE:UI splits how a control looks from whether it is checked, so a hundred checkboxes share one look. It stops blasting the screen with events and lets the view poll data instead, then skip a redraw when nothing moved. Because the UI is not welded to one display layer, a program can drive the same path with no one watching, which is how you point an agent at QA.

A Language Models Can Read, Then a Language Machines Can Run

RE:Flows is the on-ramp for designers who should not have to write engine code to try a rule. Ishida said the new graph still feels like snapping blocks, but behind the glass it becomes a standard language that more than one person can merge and debug. RE:Runtime then takes human-friendly code and auto-translates it into RE:C++, a Capcom language meant to run fast, and it packs characters and props into fixed-size boxes instead of tracking each instance alone. The point of unifying the rules is not a press-release language war. It is so a model that has seen a common syntax can read Capcom’s tree, and so the runtime can still go fast after the translation step.

RE:Dox Lands on GitHub Under Apache 2.0

The one REX piece you can clone today is RE:Dox. Capcom’s R&D account posted the repo the same day as the talk, under Apache License 2.0, as a core part of REX for the next engine. The library is a token-based structured data engine for.NET. It reads mixed formats into a compact token document, then uses that index to edit, convert, and load data. JSON, JSON5, CBOR, MessagePack, INI, and a native DOX format sit on the core path; TOML, XML, HTML, and CSV are still preview.

🚀 本日公開！

カプコンの最新データ表現・シリアライズ基盤ライブラリ「RE:Dox」を #OSS として公開しました！

RE ENGINEをさらに進化させる #REX プロジェクトの基盤技術のひとつを本日からどなたでもご利用いただけます！

🌝 ぜひ触ってみてください！

リポジトリのリンクはリプライ欄に pic.twitter.com/FKdrNNKRAS

— カプコン技研 公式アカウント (@CAPCOM_RandD) October 2, 2026

Ishida said RE:Dox and RE:Log are among the pieces going public so they can help with AI training. The GitHub README does not pitch art. It pitches speed against Microsoft’s System.Text.Json on three public data sets, run on.NET 10 with a Threadripper PRO 5975WX.

RE:DOX SPEED ON CAPCOM’S OWN TESTS

• Parallel load: canada.json deserializes at 2.84 times System.Text.Json; citm_catalog.json at 2.25 times; twitter.json at 2.34 times.
• Memory: canada.json allocates about 2.56 MB with RE:Dox against about 8.53 MB with System.Text.Json, roughly a third of the memory.
• License and install: Apache-2.0, with a NuGet package named CAPCOM.REDox.

The 30-second sample in the README is a Resident Evil joke that is also the whole point. A player named Leon at level 42, holding a handgun and a green herb, gets written to JSON. The next lines rename him Claire, add HP, drop the level, and stuff a knife into the item list. That is data moving through a public API. It is not a generated cutscene.

The February Ban on AI Assets Still Stands

Capcom already drew a hard line on what a model is allowed to put in a build. In a February 16, 2026 online briefing for individual investors, later posted as a Q&A summary, the company was asked how it handles generative AI in development. The answer is still the policy that sits under REX.

The company will not implement materials produced by generative AI into game content. On the other hand, we plan to make active use of this technology as a way to raise efficiency and productivity in the game development process. That is why we are now testing how to use it in each role, including graphics, sound, and programming.

Capcom, investor Q&A, February 16, 2026

That is the same company that now says it will not put generative AI materials in games while it opens engine guts so models can learn the plumbing. The two statements only clash if “create games together with AI” is heard as “the zombie was sampled from a model.” Ishida’s examples were automatic programs and test plays. The investor line keeps those helpers in graphics, sound, and code, and keeps their output off the disc the player buys.

REX makes that split operational. An engine unified on a common language is easier for a coding model to touch. An editor that can be driven with the screen off is easier for a QA agent to crawl. A public data library is easier to feed a trainer. None of that, on Capcom’s own wording, is a license to drop a generated texture into Resident Evil Requiem, Pragmata, or Onimusha: Way of the Sword, the 2026 games already riding this engine.

More Than 2,000 Staff Now Share One Codebase

The staff problem is the one REX cannot slogan away. Capcom told the conference crowd that almost every developer at the company now uses RE Engine, that the active user count is over 2,000, and that overseas contractors and people trained on other engines are in that mix. Logs written as raw sentences were bloating builds and resisting translation. Editors were Windows-bound. Mixed “easy for humans” and “fast for machines” languages had made the runtime messy. Those are management bugs that show up as frozen tools.

HOW RE ENGINE GOT THIS LARGE

1. 2014: Capcom starts work on the in-house engine later known as RE Engine, Reach for the Moon.
2. 2017: The first RE Engine game ships, Resident Evil 7, and the same core later spreads across horror, fighting, and hunting titles.
3. October 2023: Capcom names REX, RE neXt ENGINE, and shows an eight-part add-on plan instead of a greenfield engine.
4. February 16, 2026: Investor Q&A says generative-AI materials stay out of game content, while graphics, sound, and programming test the tools.
5. October 2, 2026: Ishida presents the five named REX systems and Capcom publishes RE:Dox on GitHub under Apache-2.0.

A house engine that large is a bet against renting Unreal. It only pays if new hires can find a button, if a Tokyo log can be read in English, and if a test agent can fire the same path a person would. Ishida’s RE:Log design, IDs instead of sentences, a compressed central store, one protocol for traffic and records, is the unglamorous half of “AI-era.” A model that cannot search last week’s crash will not save a 2,000-person studio any time.

Code Helpers Stay Off the Disc

REX is a production fix with an AI-era label, and the label is doing extra work in English. Ishida asked for an engine that models can read, that can write programs later, and that can play itself to find bugs. Capcom, the same week, put a.NET data library on GitHub and left the February asset ban in force. The Osaka student days of the conference still sit on October 17 and 18. The code that players will actually run is still RE Engine, raised in place, with Leon’s herb sitting in a public README as a serialize sample rather than as a generated hero.