The half-assed actor project mentioned by the article is probably ActorFx - which is an interesting project with some cool ideas. For exammple, you could write actors in a mix of languages like Python, JS, & C#. It had automatic state replication after each turn. Actors were observable, Rx-style. Actor behavior could be specified at runtime: you could effectively throw a JS closure into the cluster and it create an actor out of it.

I wonder, though why it became stagnant so soon and never gained momentum. I'm don't know, but I have a theory. The team were using some tech which was semi-secret at the time, which they weren't allowed to talk about: Service Fabric (known as Windows Fabric at the time). Fabric was in use in projects like Lync Server and Service Bus Server, but no one could talk openly about it.

How can you develop an open-source distributed system without being able to mention the framework which makes it all possible? Fabric handles ActorFx' high availability, service discovery, code distribution/upgrades, and their state replication. It's pretty difficult... Forum posts asking what this fabric thing was went unanswered and the people who may have been interested in ActorFx just moved on.

Regarding Orleans, there were probably a couple of internal actor frameworks in use at some large .NET houses, but they were never released to the public. I think it was more of a cultural issue than a lack of devs: .NET devs weren't used to sharing code.

Things are getting better. The community around Orleans is great (come join us on Gitter! https://gitter.im/dotnet/orleans) and the ecosystem as a whole feels to be gaining momentum.