.NET Orleans
&gt; It was created by Microsoft Research and introduced the Virtual Actor Model as a novel approach to building a new generation of distributed systems for the Cloud era.<p>Okay, sounds like an academic, Microsofty take on Erlang&#x27;s Actors? But from docs, sounds like it&#x27;s at least used in practice at MSFT:<p>&gt; Since 2011, it has been used extensively in the cloud and on premises by several Microsoft product groups, most notably by game studios, such as 343 Industries and The Coalition as a platform for cloud services behind Halo 4 and 5, and Gears of War 4, as well as by a number of other companies.<p>&gt; Orleans was open-sourced in January 2015, and attracted many developers that formed one of the most vibrant open source communities in the .NET ecosystem.