Terrarium was a concept that was probably ahead of its time. While the game did allow developers to transfer some form of state between parents and offspring, it was a feature that was never used in successful agents. Instead, developers just optimized their code for a particular set of fixed strategies, which in many cases turned out to be a lot of code. The following is an example screenshot of a Terrarium client running in ecosystem mode:
Original Microsoft Terrarium
Now, the bottom line is that we are not going to be able to replicate the entire Terrarium connected ecosystem concept in one chapter. The elegance that was the Terrarium network ecosystem infrastructure could possibly take several chapters to explain. Instead, our goal is going to build a multi-agent multi-brain ecosystem that is designed to teach you more about building an ML-Agents environment...