Strategy games with customizable unit actions?

I was reading a story that mentioned von Neumann machines and other self replicating robots breaking down planets for resources and space exploration and it got me wanting to play a game focused on that, where you can intially custom-program your units and then let them out to do what you programmed and see what happens.

Does anyone know of a game like this?

It doesn't have to be robots or space specifically, I'm just looking for something resource-management-y with more customizable unit actions than age of empires or civ.

Thanks a bunch!