Causal block diagrams are a formalism to model systems using mathematical values. However, their text output can be difficult to visualize. This paper aims to describe a system where causal block diagrams can be visualized using a Java simulation. This is achieved by embedding causal blocks within a behaviour tree formalism. With this new hybrid formalism, a number of advantages are realized such as increased flexibility and expressibility. Two simulations using these hybrid trees are presented, as well as a discussion of the new formalism’s suitability to these problems. These simulation experiments are the circle test and a personal space simulation, and the resulting hybrid trees are also examined.