Yuji Horii, the creator best known for the Dragon Quest role-playing series, has used Anthropic’s Claude tools to make a short browser game inspired by his earlier mystery title, The Portopia Serial Murder Case.
Released for PC in 1983, Portopia is regarded in Japan as an important early adventure game and is credited with helping set the stage for Nintendo’s Famicom Detective Club series. Outside Japan, however, it has more recently attracted attention through Square Enix’s poorly received 2023 attempt to rebuild it using AI.
A new interrogation-room experiment
Horii’s own experiment is called Komiya in the Interrogation Room. The compact browser-based game takes place during the questioning of Komiya, a 72-year-old suspect connected to a possible safe robbery.
Komiya repeatedly lies, leaving the player to select from different lines of questioning and work out what really happened. The interrogation is governed by two meters: Agitation and Resistance. Both change in response to the player’s approach, and either can eventually reach 100, at which point Komiya may stop answering altogether.
When I made The Portopia Serial Murder Case for PC, I created the story, drew the artwork and programmed the game myself. Now, with AI, someone who cannot draw or code can give instructions and make a reasonably complete game alone. It is genuinely astonishing.
— Yuji Horii, October 11, 2026
Horii said he spent approximately 30 minutes creating Komiya in the Interrogation Room before sharing it. His comments highlight how quickly generative tools can turn a concept into a playable prototype, even when the creator is not handling the art and programming directly.
Horii’s continuing enthusiasm for AI
The veteran designer, who also co-wrote Chrono Trigger, has been openly enthusiastic about AI in recent months. His posts have included praise for the technology’s improving reliability, including the claim that it “hardly ever” makes things up anymore.
The wider Dragon Quest brand has also appeared in several generative-AI promotional activities in Japan, including campaigns in partnership with Google’s Gemini.
For more coverage of changing game-development tools and the wider arcade industry, explore RETROCADE’s arcade videos and DIY arcade projects.
What comes next for Portopia?
Horii is currently working on the scenario for Dragon Quest XII, the next mainline entry, which underwent a major reboot during the past year.
Meanwhile, The Portopia Serial Murder Case looks set to receive a developer- and artist-driven remake from G-Mode next year. That project will provide a notable contrast with Horii’s rapid AI-built browser experiment: one is a traditional remake led by a development team, while the other was created as a brief personal test.
For readers interested in turning classic games into a home setup, RETROCADE’s arcade machine buying guide covers the key decisions involved in choosing a cabinet.
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