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Watch trailer on Steam ↗Crimsooon Sun
Old Retina Museum · Published by Old Retina Museum
7 user reviews — 86% positive (7 reviews) · 8 achievements
Last updated 28 Sept 2026
No choices but deduction. No game over. No multiple endings. A mystery "novel" adventure you can play with the same focus as reading a detective novel. Defy the sun with twenty-six bullets—even if the revolution of the heavenly spheres cannot be stopped.
£2.65
Lowest price we've ever recorded
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Price history
Adventure, Casual · 2026 · More under £5 games
About this game
No Choices But Deduction.
No Game Over.
No Multiple Endings.
Your choices will change neither the story nor the movement of the celestial bodies.
The only thing you can do is pull the trigger—and deduce.
"Crimsooon Sun" is a short mystery adventure designed with a singular concept: "A mystery game you can play with the same level of focus as reading a detective novel."
The story takes place in Shirase, a regional city in the Tohoku region. It begins with the return of Mio Fujimaru, a university student who had been missing for nearly six months. She remains silent about her disappearance. However, a video exhibited at the university festival reveals a chilling sight: Misao being pushed down a wedding aisle in a wheelchair by a mysterious "the Faceless Man," while "the Dual Suns" are reflected in the window.
This is a mystery "novel" adventure. When reading a detective novel, one doesn't always have a perfect, logical solution like the detective in the story. Often, we rely on vague intuitions:
"Something about this statement feels like a lie."
"This person seems suspicious."
"This description might be related to a trick."
Such intuitive reasoning often clashes with traditional game systems that require picking the "correct" choice to proceed.
Inspired by "Mikagura Shojo Tanteidan" (Mikagura Girls' Detective Agency), a classic title released for the PlayStation by Human Entertainment, this game cuts away all unnecessary choices and branching paths. Instead, you "pull the trigger" whenever something piques your interest. With the 26 bullets of information you’ve gathered, your only task is to deduce the truth.
Defy the sun with twenty-six bullets.
Even if the revolution of the heavenly spheres cannot be stopped.
Streaming Guidelines
There are no specific restrictions. Please treat it as you would a mystery novel.
Demo
You can play up to the end of Chapter 1, out of a total of 3 chapters (plus a prologue and an epilogue).
Save data will automatically carry over to the full version.
Please note that achievements are not available in the demo. However, once your save data is carried over to the full game, your achievements will be verified at the title screen.
System Requirements
Will my PC run this? →Minimum
- OS: Windows 10
- Processor: 2.0 GHz Dual Core or similar
- Memory: 4 GB RAM
- Graphics: DirectX 10 compatible graphics card with 1GB VRAM
- DirectX: Version 10
- Storage: 512 MB available space
- Sound Card: DirectX compatible sound card
Supported Languages
Latest news
Patch NotesOfficial
Update v2.0.9
Crimson Sun has been updated to v2.0.9.That said, this update only includes corrections to typos and wording. There are no changes to the actual content of the game.Please note that the demo remains at v2.0.6, as none of the changes in this update affect the demo. v2.0.9-Fixed typos and improved wording.Read full article on Community Announcements (burikino)Patch NotesOfficial
Launch and Update v2.0.6
Crimsooon Sun was released yesterday on the 17th. To celebrate the release, it is currently 10% off at $2.69 for the first 14 days. Although the release version was stated as v2.0.4 in the previous article, bugs and issues were found before launch, so the following fixes have been applied, making the official release version v2.0.5. Additionally, we have rolled out update v2.0.6 today to address audio volume adjustments. v2.0.5 ・Increased mouse wheel scrolling speed in the table of contents. ・Fixed an issue where the loading screen animation did not work in the demo version. ・Fixed the credit notation. v2.0.6 ・Adjusted ambient sounds (excluding the background music playing in the cafe) to be quieter. ・Adjusted the volume of the starting buzzer and intercom to be quieter. If you encounter any other bugs, please report them in the discussion thread ( https://steamcommunity.com/app/4631660/discussions/0/569291508114600377/ ) or contact us through any other convenient method.Read full article on Community Announcements (burikino)AnnouncementsOfficial
Crimsooon Sun Release Date Announced: July 17
I'm happy to announce that Crimsooon Sun has successfully passed Steam review and will be released on Friday, July 17. I'd like to take this opportunity to introduce the game. Overview Crimsooon Sun is the PC version of a detective novel adventure originally released for iOS and Android (Japanese only) at the end of December 2024. The story was inspired by a real report of Dual Suns phenomenon that I encountered at an academic conference. Although it is a mystery game, it is not a murder mystery, and it contains no graphic or grotesque content. For the PC release, the interface has been redesigned for keyboard, mouse, and controller play. The game also includes a full English translation, improved presentation, additional illustrations, and new loading animations. Other than these improvements, however, the story and gameplay remain essentially unchanged from the original release. Genre and Gameplay As described on the store page, Crimson Sun is a DETECTIVE NOVEL ADVENTURE. What does that mean? Simply put, the game has no story choices outside of deduction, no minigames, no game overs, and no multiple endings. It is designed to be experienced as a novel. The basic gameplay is similar to a traditional visual novel without branching choices. However, it features a unique information-gathering mechanic called the Trigger System. The Trigger System was inspired by the one used in Mikagura Shoujo Tanteidan (Mikagura-Girls-Detective). Once during each section of the story, you may pull a Trigger to obtain a "bullet," which also unlocks a new Trigger Note containing additional information. There is, however, one major difference between the two games. In Mikagura Shoujo Tanteidan, pulling the correct Trigger awards points. You must earn enough points before you can proceed to the deduction phase, meaning the game immediately tells you whether your choice was correct. Crimsooon Sun works differently. When you pull a Trigger, you simply receive new information. At that momen...Read full article on Community Announcements (burikino)
