SpatialOS

SpatialOS
Information
Type	Distributed simulation platform
Industry	Video games, simulation
Developer	Improbable
License	MIT License (GDK for Unity and GDK for Unreal plugin only)
Release Date	November 11, 2015 (announced); December 13, 2016 (open alpha); March 2, 2017 (open beta)

SpatialOS is a cloud platform made by the London company Improbable for running large multiplayer games and simulations across many servers at once. Improbable announced it in November 2015 as a distributed operating system for large-scale simulation, and early coverage pitched it at virtual reality worlds as well as city, economic and traffic models. In its later documentation Improbable described SpatialOS as "a platform-as-a-service that runs and manages online games in the cloud", in which many server programs share a single game world that looks seamless to players.

PCGamesInsider.biz described Bossa Studios' Worlds Adrift as the first commercial product to use the technology. Early VR projects included HelloVR's social world MetaWorld and NetEase's open-world role-playing game Nostos, which was playable in VR. In January 2019 a licensing dispute with Unity Technologies briefly put SpatialOS games built with Unity in doubt, and Epic Games and Improbable answered with a US$25 million developer fund. Several flagship SpatialOS games were later shut down or cancelled. The archived README of Improbable's Unity development kit calls the original service the "SpatialOS legacy platform", says the kit is frozen, and asks users to migrate to "SpatialOS running on zeuz"; Improbable had acquired the backend company Zeuz in early 2020.

Reviewed 19 October 2026. Rechecked every cited source for dates, names, quotes, figures, GDK release history and current status as of October 2026. About review dates.

History

Announcement and alpha

Improbable was founded in 2012 by Herman Narula and Rob Whitehead. Narula announced the platform, then written "Spatial OS", at the Slush conference in Helsinki on November 11, 2015. The London company had raised US$20 million from Andreessen Horowitz in March of that year. He said it could plug in engines such as Unity along with mobile and VR hardware, and that it could scale to millions of users for consumer products such as virtual reality. Worlds Adrift, which Narula described as a world the size of Israel containing four million entities, was demonstrated on stage. TechCrunch reported that projects then in development also included a complete model of London for traffic, population and other simulations.

HelloVR, a small studio in Richmond, California, revealed MetaWorld in July 2016. It was a shared virtual world for the HTC Vive built on SpatialOS. In a demo for GamesBeat the playable area was about an acre, and the studio said the world could eventually cover 10,000 square miles. It used SpatialOS for networked physics and persistence, so an object dropped in one place stayed there for later visitors. Narula said HelloVR had designed MetaWorld around room-scale VR.

On December 13, 2016, Improbable opened an alpha of SpatialOS to all game developers. It also announced a partnership with Google under which Google Cloud Platform would run the service, and a SpatialOS Games Innovation Program that gave qualified developers subsidized access to the platform. At that point the studios already working with SpatialOS included Bossa Studios (Worlds Adrift), Spilt Milk Studios (Lazarus), HelloVR (MetaWorld), Entrada Interactive (Rebel Horizons) and Soulbound Studios (Chronicles of Elyria). UploadVR noted that the program was not aimed specifically at VR, though it could help VR developers with high development costs.

Open beta and growth

At GDC 2017 Improbable announced that SpatialOS would enter open beta on March 2, 2017. The platform had supported only Unity until then, and the company showed an experimental build with Unreal Engine support using its own game Dusk. It also named the first studios in the Google-backed innovation program, among them Klang (Seed), Spilt Milk Studios (Lazarus), Soulbound Studios (Chronicles of Elyria) and Ninpo Game Studio (Vanishing Stars: Colony Wars).

Not every partner stayed. In January 2018 Soulbound Studios said Chronicles of Elyria would no longer use SpatialOS. The studio said some of the game's non-spatial systems did not fit the architecture and that it worried the game's large size would make SpatialOS too expensive in the long term. Worlds Adrift entered Early Access in May 2018.

NetEase showed Nostos, a post-apocalyptic open-world RPG playable in VR or on a standard PC, at Gamescom 2018. Road to VR reported that the game was to support SpatialOS, although the feature was not active in the demo; a NetEase spokesperson said it would be available at launch.

In a November 2019 announcement of an extended partnership, Google Cloud said Improbable had grown from about 100 employees in 2016 to more than 500, had raised more than US$550 million, and had opened Improbable Game Studios that year, with studios in the UK, the US and Canada making SpatialOS games. The same release said SpatialOS used Google Compute Engine for its virtual machines, gRPC to coordinate its microservices and Kubernetes for container management, and that Improbable was adding support for the Open Match matchmaking framework.

2019 Unity terms of service dispute

On January 10, 2019, Improbable published a post titled "Unity's block of SpatialOS". It said Unity had changed clause 2.4 of its terms of service on December 5, 2018, and clarified to Improbable on January 9 that the change made it a breach of terms to create or operate SpatialOS games with Unity. Improbable also said Unity had revoked its own ability to work with the engine. It promised an emergency fund for affected developers and said it would release the code of its SpatialOS GDK for Unity under the MIT license.

Unity co-founder and CTO Joachim Ante replied the same day that Improbable's post was "incorrect". He wrote that Unity had ended its relationship with Improbable after a failed negotiation over terms violations, that it had warned Improbable in person more than a year earlier and in writing six months earlier, and that it had turned off Improbable's Unity Editor license keys two weeks before. He also said live and in-production games using SpatialOS were not affected. The same day Improbable posted a second statement apologizing for the uncertainty the event "we instigated" had caused, and saying that "both sides have certainly made errors".

Developers caught up in the dispute included Bossa Studios with Worlds Adrift and Spilt Milk Studios with Lazarus, both live, plus studios with unreleased games such as Arcane Reality (Overduty VR) and Dynamight Studios (Fractured). In a joint post dated January 11, 2019, Epic Games founder Tim Sweeney and Narula announced a combined US$25 million fund "to help developers transition to more open engines, services, and ecosystems". The money was to come from Unreal Dev Grants, Improbable developer assistance funds and Epic Games store funding. The post also said Improbable was building an open Unreal integration for SpatialOS.

On January 16, 2019, Unity revised section 2.4 of its terms so that developers could use any third-party service that integrates with Unity, whether or not Unity supported it. It also began publishing its terms on GitHub. Engadget reported that Improbable's license keys were reinstated and that developers could legally build games using both Unity and SpatialOS. Ante added that Unity did not consider Improbable a partner and could not vouch for how its service worked with Unity. The Register wrote that the change did not appear to have repaired Unity's relationship with Improbable. In a Reddit AMA the same day, Unity CEO John Riccitiello said Unity had been right to terminate Improbable's licenses.

Game closures

Bossa Studios announced in May 2019 that Worlds Adrift would close, saying it was no longer commercially viable. In February 2019 Bossa's chief technology officer, Sylvain Cornillon, had written that a fundamental change in the underlying SpatialOS architecture had left the game stuck on an older version, and that moving to the new one would mean rewriting more than 40 per cent of its code base, with the server-side code in a different language. The studio said the game could not be released as open source because it was partly built with third-party tools, plugins and licensed code. It closed on July 26, 2019. Days later Automaton Games, the developer of the SpatialOS-based shooter Mavericks: Proving Grounds, went into administration. Mavericks had been planned for up to 1,000 players, with a 400-player battle royale mode. PC Gamer noted that it was not the first SpatialOS-powered game to shut down that summer.

Nostos reached Steam in December 2019 with optional VR support and came to PlayStation 4 a year later without VR. NetEase announced in March 2021 that it would close on June 16, 2021, citing "changes in business development".

Scavengers, from Improbable's own Midwinter Entertainment studio, entered early access in April 2021. A September 2021 report in Sifted said a number of SpatialOS games had been scrapped and that developers had criticized the platform as expensive and difficult to use. In February 2022 Improbable sold its majority stake in Inflexion Games to Tencent. Inflexion CEO Aaryn Flynn said its game Nightingale would no longer use SpatialOS, a decision the studio had made the previous summer for design reasons. Improbable sold Midwinter to Behaviour Interactive in May 2022 and cancelled the planned console versions of Scavengers. In November 2022 Improbable announced that it would shut down the PC version's servers on December 16, 2022, without the game leaving early access, citing a decline in the player base.

Architecture

Improbable's documentation describes an entity-component-worker design. The game world is held as a database of entities, each made up of components that store data. A Rabbit entity in the documentation's example has Position and Health components, while a Lettuce entity has Position and Edible components. Developers define every component in a schema that lists its properties, events and commands. SpatialOS generates APIs from that schema, which worker code uses to read and write component data.

Server-side game logic runs in "server-workers". Each server-worker instance is responsible for part of the world, called its area of authority, and sees a slightly larger area so it can simulate the boundary correctly. Instances do not know about each other and may run on different machines. Developers split the work through load balancing, either by "zoning" (a grid of areas of authority) or by "offloading" (splitting work by entity type). Client-workers run on players' machines. They also see only part of the world, but they can see across server-worker boundaries.

Each deployment has one instance of the SpatialOS Runtime, which has three parts:

Part	Role
Entity database	Holds the canonical store of all entity data
Bridge	One per worker connection; forwards the worker's requests and sends it updates only for the part of the world it may read
Load balancer	Coordinates which worker instance has write access to each entity

Workers never talk to the entity database directly. Production games always run on Improbable's cloud hosting, while a local deployment on a development machine can emulate it during testing. Improbable said this design let games scale past a single server, keep long-lived persistent worlds and run several types of server-worker for different systems.

Development kits

Improbable offered integrations for Unity and Unreal Engine, plus a lower-level SDK for other engines. The SpatialOS GDK for Unreal combined a plugin with a fork of Unreal Engine that Improbable modified to turn the engine's single-server model into a distributed one. Using it required a linked Epic Games account. SpatialOS for Unreal 2020.2 added AI Offload, which runs non-player characters on a second game server. Improbable developed it with Midwinter Entertainment for Scavengers and reported that, in its own stress tests against native Unreal Engine, a test scenario supported 101% more NPCs at 140 players.

Kit	Last release	Repository status
SpatialOS GDK for Unity	0.4.0 (September 14, 2020)	Archived January 18, 2022
SpatialOS GDK for Unreal	0.11.0 (September 3, 2020); last pre-release 0.14.1 (September 17, 2021)	Archived August 29, 2024

Both repositories are published under the MIT License.

Research

In a 2018 paper in MATEC Web of Conferences, Jarosław Koszela and Maciej Szymczyk proposed a cloud model for scaling virtual simulation, presented SpatialOS as a commercial example and ran performance tests on it. They argued that distributed virtual simulation allows larger and more detailed simulation models with thin clients.

Current status

The archived GDK for Unity repository says it holds the last version compatible with the "SpatialOS legacy platform" and that the kit is frozen for users who had not moved to "SpatialOS running on zeuz". It asked existing users to contact Improbable about migration before December 30, 2021. Improbable had acquired the backend company Zeuz in early 2020.

In September 2021 the company unveiled technology known internally as Project Morpheus, designed to host up to 10,000 players in the same space; Narula said it would solve many of the problems developers had raised. In December 2023 CNBC reported that Morpheus was Improbable's primary product, that a series of games built on "Improbable's original SpatialOS technology" had been cancelled (naming Nostos, Worlds Adrift and the console version of Scavengers), and that Improbable had sold its defense business that September. As of October 2026, Improbable's website describes the company as a venture builder working on AI, Web3 and the metaverse and does not list SpatialOS. No formal end-of-life announcement for SpatialOS was found.

See also

• Improbable
• Worlds Adrift
• Persistent world
• Social VR