Casualties: Unknown (developed by Orsoniks and published by Oro Interactive; formerly Scav Prototype) drops a stranded expedition crew into an 11-layer high-gravity subterranean cavern where every fall, laceration, fracture, and syringe injection is governed by an unforgiving anatomical medical simulation.
Standard hit points do not exist. Every impact, shrapnel blast, or bite targets individual limbs and organ systems (Head, Thorax, Abdomen, Arms, Legs). Arterial lacerations drain blood volume in liters per minute, requiring immediate Dressings, Plastic Dressings, Tourniquets (INT 9), or surgical sutures before hypovolemic shock triggers cardiac arrest.
Recognizing advanced pharmaceuticals and assembling improvised survival gear depends on your survivor's Intelligence (INT) stat. Scavenge crates, dismantle mechanical debris, and combine components into Splints, Welded Splints, Campfires, Makeshift Digging Tools, and Backpack storage upgrades.
Containers and syringes hold up to multiple reagents that react dynamically. Drinking versus injecting a fluid produces radically different physiological outcomes: Saline restores blood volume intravenously, Ceftriaxone halts systemic sepsis, Antirad purges radiation sickness, and Fentanyl or Morphine suppress lethal pain.
Descend from Layer 1 (Frozen Ruins / Frozen Chasm) through Gravel Lands, Overgrown Depths, Fungal Pools, Crystalline Hollow, Geothermal Vents, Dried Desert, Wasteland, and Crimson Ascent down to Layer 11 (Where We Must Reach), while navigating high gravity and thermal extremes.
Choose between Experiment (balanced baseline), Milky / 269 (specialized resilience and biological quirks), and Dune / 705. Develop 7 distinct skill trees covering Strength, Resilience, Intelligence, Scavenging, Stealth, Mobility, and Biotech.
Survive automated security turrets, proximity landmines, radiation pockets, and hostile subterranean fauna. Track every trigger in the 5-stage Mercenary questline to unlock all 5 endings and complete all 40 official Steam achievements.
Casualties: Unknown evolved from Orsoniks' original itch.io builds of Scav Prototype into the commercial Release 1.0 launch on Steam (AppID 4576490) on November 9, 2026. The table below records the verified version history and baseline environmental telemetry.
| Version ID | Release Milestone | Release Date | Platform Surface | Verified Mechanical Scope |
|---|---|---|---|---|
| v1-0-release | Release 1.0 (Full Steam Launch) | 2026-11-09 | PC (Steam Windows / Linux) | Full 1.0 release adding Layers 6–11, 3 playable characters (Experiment, Milky, Dune), 3 endings, Endless mode, 40 Steam achievements, prosthetics, item customization, and opiate/venom HUD bars. |
| demo-v7-0 | Demo Update 7.0 | 2026-06-04 | PC (Steam Demo AppID 4576510) | Major pre-release demo update expanding medical interactions, container UI, and Layer 1–5 balance. |
| demo-v6-0 | Steam Reveal & Demo 6.0 Launch | 2026-04-20 | PC (Steam Demo AppID 4576510) | Initial Steam Demo launch rebranding Scav Prototype to Casualties: Unknown with a reworked cardiovascular simulation and 5 playable layers. |
| itch-scav-prototype | Scav Prototype (Itch.io Builds v4.1–v5.1) | 2024-12-31 | PC (Itch.io) | Early prototype builds released by Orsoniks on itch.io accumulating over 300,000 downloads prior to the Steam transition. |
Interactive 18-condition body-system diagnostic workbench, bleed rates, and surgical procedures.
45-item survival & crafting catalog plus 25 dedicated item detail pages with INT requirements.
73-fluid color swatch chart, oral vs IV effects, antidotes, and biochemical mixing hazards.
All 11 subterranean layers, depth ranges, ambient temperatures, and special sub-layers.
3 playable survivors (Experiment, Milky, Dune) and 7 skill tree progressions.
25 hostile fauna, automated turrets, landmines, and hazardous cave flora.
All 5 endings and the complete 5-stage Mercenary questline walkthrough.
All 40 official Steam achievements with 100% official icons and global unlock rates.
Developer console commands, spawn syntax, NPC trader barter rules, and terminal minigames.