MIMESIS horror game adds Proton-compatible Paranoia system in Off the Rails update

ReLU Games has released the Off the Rails update for MIMESIS, a four-player co-op horror title that uses Proton for Linux and Steam Deck compatibility. The update introduces the Paranoia system, which alters each player's visual and auditory experience based on their individual contamination level, creating divergent realities within the same session. This compounds the game's existing AI-driven mimicry mechanic, where enemies can replicate the appearance, voice, and behavior of teammates.

The update also delivers a new film studio map with blended indoor-outdoor traversal, additional enemy types, traps, gear for expanded inventory capacity, communication tools, and a revised user interface. The game maintains its Steam Deck Verified status, which the source notes as significant given the audio-dependent gameplay. MIMESIS has sold over two million copies and holds an 89% Very Positive review score on Steam.

Proton compatibility and gameplay systems

• Proton compatibility: The Windows-native game runs on Linux and Steam Deck through Valve's Proton compatibility layer, with verified Steam Deck support confirmed by the source.
• Paranoia system: A new per-player contamination mechanic that individually alters visual and audio perception, creating asymmetric information between teammates in the same session.
• AI mimicry enhancement: The existing enemy AI that copies player appearance, voice, and movement patterns now incorporates additional behavioral learning and environmental reactivity.
• Map architecture: The new film studio level features contiguous indoor-outdoor spaces designed to reduce loading boundaries and enable more open traversal.
• Audio subsystem dependency: The source highlights that clear audio reproduction through Proton is functionally critical, as voice-based deception and hallucination cues are central to gameplay.

Why it matters

For Linux gamers and Steam Deck owners, this update reinforces that Proton remains the practical path for accessing Windows-first multiplayer titles with complex audio and AI systems. The Steam Deck Verified status provides a baseline compatibility guarantee for a game genre where latency-sensitive voice communication and consistent frame timing directly affect playability. The continued Early Access development also offers a test case for how Proton handles evolving anti-cheat and synchronization requirements in asymmetric co-op environments.