Casualties: Unknown is an upcoming survival video game developed by Orsoniks and published by Oro Interactive that is scheduled to be released in 2026. Players play as an Experiment, a test subject sent down to explore the depths of an alien planet. The game revolves around navigating and safely descending the planet's cavernous layers while avoiding and treating injuries, hunger, and thirst. The game centers around robust health systems and difficult resource management, challenging players to avoid death in numerous ways as they go as far down as they can.
As of mid-2026 the game had not received a full release; a playable demo became available on the digital storefront Steam on April 20, 2026.
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Gameplay
Casualties: Unknown is a cave-exploration survival game in which the player controls a captive test subject called an Experiment placed on a hostile alien planet and tasked with retrieving lost cargo. The full game is planned to include eleven procedurally generated underground "layers" of increasing difficulty; the public demo makes five of these layers available. A press release describes the game as featuring a "fully simulated limb and cardiovascular system," requiring the player to bandage wounds, treat infections and manage blood loss to avoid losing consciousness. The player character's in-game mood is also tracked as a survival mechanic alongside physical injury.
A gameplay feature list published by the outlet GamingOnLinux additionally credits the demo with character traits that improve over a run (intelligence, strength and resilience), three playable characters with distinct playstyles, roughly 300 collectible items, and adjustable loot and danger settings accessible from the main menu. The same outlet reported that the demo ran under Proton on Linux systems.
Development
Casualties: Unknown is developed by Orsoniks, described in a publisher press release as a designer, programmer, composer and artist. According to the same release, the game began as a small personal project that gained a wider following after early alpha builds were distributed for free on the platform itch.io, with the publisher reporting that the game had surpassed 300,000 players on that platform prior to its Steam debut. The game is built using the Unity engine. GamingOnLinux described the setting as one in which an artificially created "Experiment species" is sent to retrieve technology from a hazardous alien world, and noted the interface as an area needing further refinement ahead of a full release.
Release
A free demo of Casualties: Unknown, covering five of the game's planned eleven layers, was released on Steam on April 20, 2026, alongside a publisher-issued press release and trailer. IGN subsequently published an official demo launch trailer and a separate "full run" gameplay video for the title. As of mid-2026, the full version of the game remains unreleased, with listings citing a tentative release window in Q4 2026.
Reception
Casualties: Unknown received a largely positive response on the basis of its free demo. Games outlet GamingBible described the demo as "brutally difficult but emotionally gripping" and reported that it had drawn an "overwhelmingly positive" Steam user-review rating despite the game having little prior public profile, noting that user reviews singled out its damage-simulation and physics systems for praise while citing its difficulty as the main point of criticism. Rock Paper Shotgun published a piece comparing the game to Noita, per the article's title. Writing for OpenCritic in a piece syndicated from TheGamer, journalist Josh Coulson identified Casualties: Unknown as the highest-rated demo of more than 8,500 available during the June 2026 Steam Next Fest, citing a score of 93.08 percent based on user reviews tracked by SteamDB, and described its core loop as combining cave exploration with the board game Operation. GamingOnLinux also rated the demo positively, calling its exploration and injury systems intense, though it noted that the user interface needed further work.