Note: Information provided comes from public sources, and is not under NDA to the best of my knowledge.

When the COE Kickstarter launched SpatialOS was a cornerstone of the design which was going to help bring the game quickly to market.

In 2018 SBS decided to not use use SpatialOS for several reasons, instead replacing it with a number of in house / package solutions.

These included using RabbitMQ, Docker Swarm, NodeJS, PostgreSQL and VoxElyria.

Heard over on the Grapevine recently, Caspian shared some information which indicates another major shift in development direction & tools is currently under investigation.

Team is investigating using C++, C# or Rust instead of NodeJS as its process overhead and large memory footprint make it impractical for creating large scale worlds like COE.

Docker (Swarm) will likely be replaced with Kubernetes. (it's what all the cool kids are doing these days, even where I work)

They are also considering other programming languages for the service mesh.

While they currently are using RabbitMQ for messaging protocol, they are experimenting with alternatives atm.