Sound Design
The sound design in The Expanse: Osiris Reborn reflects the same commitment to authenticity that defines the rest of the game. Audio Director Sergey Eybog leads the team responsible for creating an audio experience that respects the physics of The Expanse universe while still delivering the gameplay feedback players need in a cover-based shooter. The approach was detailed in a March 2026 developer diary, where Eybog laid out the philosophy: the game is "not an astronaut simulator, but a cover shooter," meaning the team had to balance scientific accuracy with the practical needs of a fast-paced action game.
The Challenge of Sound in Space
In real space, sound does not propagate because there is no medium to carry the vibrations. The Expanse has always respected this fact; in the books and TV show, space is largely silent except for what characters hear through their suits and radio. Osiris Reborn follows the same rule, but the challenge for a video game is that sound is one of the primary ways players receive gameplay information. Gunfire direction, enemy movement, companion calls, grenade warnings: all of these are communicated through audio in a typical shooter.
Eybog's solution was to replace traditional audio channels with alternatives that are both scientifically plausible and functionally clear. Instead of hearing a gun fire across the room, the player hears vibrations transmitted through surfaces and their own suit systems. Instead of hearing an explosion's boom, they see the flash and debris while feeling a rumble through their magnetic boots. The result is a zero-gravity combat experience that sounds distinctly different from standard-gravity fights, creating two separate audio identities for the game's two combat environments.
Sound Channels in Vacuum
When the player is in vacuum (either inside a depressurized station section or in open space), audio comes through several distinct channels, each grounded in the physics of the situation.
Sound Channel | Source | Description |
|---|---|---|
Breathing | Spacesuit internal | Always audible. The player character's breathing rate increases during combat and physical exertion. Acts as a subtle stress indicator. |
Magnetic Boot Vibrations | Surface contact | Transmits tactile feedback from the surface the player walks on. Nearby activity (enemy footsteps, machinery, explosions) travels through the station hull and into the boots. |
Weapon Tremors | Physical contact | Firing a weapon in vacuum produces no audible report. Instead, the player hears the mechanical action of the weapon as vibrations through their hands and suit. Enemies' weapons are similarly muffled. |
Radio Communications | Helmet speakers | Companion callouts, mission updates, and enemy chatter (if intercepted) come through the helmet radio. EM interference in certain areas can distort or cut out radio signals. |
Suit Warning Systems | Spacesuit HUD | Automated audio cues for suit integrity breaches, low oxygen (if applicable to a specific scenario), incoming threats detected by suit sensors, and proximity warnings. |
The transition between pressurized and vacuum environments is handled dynamically. When atmosphere vents from a room (due to a hull breach or the player opening an airlock), sound fades progressively rather than cutting out instantly. The reverse happens when the player enters a pressurized area: ambient station noise gradually returns as air fills the space. This smooth transition prevents jarring audio shifts and reinforces the physicality of atmosphere as something the player can observe leaving or arriving.
EM Interference
Electromagnetic interference is an environmental hazard that affects radio communications. In certain areas of the game, particularly near heavy machinery, damaged power systems, or specific story-related locations, EM interference distorts or cuts out radio signals. This means companion callouts, mission updates, and intercepted enemy communications can become garbled or disappear entirely. Losing radio contact in the middle of a firefight forces the player to rely on visual cues and suit vibrations alone, creating a heightened sense of isolation.
The EM interference system is not just atmospheric set dressing. It has gameplay implications: losing radio contact means losing access to companion tactical callouts that would normally alert the player to flanking enemies or incoming threats. Players who enter high-interference zones need to compensate by being more visually attentive and using the Tactical Visor more aggressively.
Pressurized Environment Audio
In pressurized environments (station interiors with atmosphere, planet surfaces with domes), audio functions more traditionally. Gunfire sounds like gunfire. Explosions have bass and concussive impact. Companions shout warnings across the room. Ambient sounds of station machinery, crowd chatter, and environmental effects fill the background. The contrast between pressurized and vacuum audio is one of the game's strongest atmospheric tools, and the developers use environmental depressurization as a mid-combat event that shifts the audio landscape in real time.
Main Theme and Original Score
The game's main theme was composed by Pawel Perepelica, who also scored Pathfinder: Wrath of the Righteous and Warhammer 40,000: Rogue Trader for Owlcat Games. Perepelica's involvement provides musical continuity with Owlcat's previous work while the composition itself reflects the different tone of Osiris Reborn: less high-fantasy orchestration and more atmospheric, tension-driven sci-fi scoring.
The main theme was publicly revealed on November 7, 2025, shortly after the game's announcement. Early reactions from the community were positive, noting the theme's blend of ambient electronics with orchestral elements that evoke the vastness and danger of space travel. The full original soundtrack will accompany the game at launch. A digital copy of the OST is included in the Miller's Pack and Collector's Edition pre-order tiers.
Eybog's Design Philosophy
In the March 2026 developer diary, Eybog emphasized that the sound team's goal was to make the player feel the difference between fighting in atmosphere and fighting in vacuum on a gut level, not just an intellectual one. "You should know where you are with your eyes closed," he said. Every combat encounter in vacuum is meant to feel tense and slightly wrong compared to the more conventional audio of pressurized fights. The quietness of vacuum combat, broken only by breathing and vibrations, creates a sense of vulnerability that no amount of armor or firepower fully dispels.
The team also worked to ensure that audio cues remain readable in both environments. A player who hears a specific vibration pattern through their boots in vacuum should understand that it means the same thing as the corresponding sound in atmosphere: an enemy is approaching from behind, an explosion is about to go off nearby, or a companion is calling for help. The two audio palettes are different in presentation but parallel in information.