Unity has blocked the use of real-time multiplayer platform SpatialOS, leaving many developers who rely on the service in a state of limbo.
A change to the Unity terms of service means all existing SpatialOS titles, including production games and those still in development, are now in breach of the company's license terms.
SpatialOS creator Improbable broke the news in a blog post, and explained Unity has also revoked its ability to continue working with the engine for breaching the newly changes terms of service in an unspecified way.
That means the company will no longer be able to fully support Unity developers, some of whom have been forced to shut down the servers for their SpatialOS projects.
Although Improbable believes the "unfortunate and counterproductive action" to be a simple error in judgment or coordination failure on Unity's part, the company is worried by the fact the change occurred during an open commercial negotiation with the engine maker.
"Overnight, this is an action by Unity that has immediately done harm to projects across the industry, including those of extremely vulnerable or small scale developers and damaged major projects in development over many years," wrote Improbable.
"Games that have been funded based on the promise of SpatialOS to deliver next-generation multiplayer are now endangered due to their choice of game engine. Live games are now in legal limbo.
"All customers who entered into a relationship with us and Unity previously did so on the good faith understanding that the terms they signed up to, sometimes years ago, would allow them to be successful and not carry additional charges."
Improbable is now urgently seeking a solution to the situation, and says it will do everything in its power to solve the issue in good faith with Unity -- with the ideal outcome being a reversal of the terms change.
In the meantime, the company has pledged to help developers using SpatialOS with Unity finish, release, and operate their games, and is setting up an emergency fund for partners who'll now be thrown into the financial mire.
Improbable will also be fully open-sourcing the SpatialOS Game Development Kit for Unity under the MIT license, in the hope it might assist individual customers in some way. Those interested can find out more about the dispute over on the Improbable blog