GNS3 - GNS3 is a graphical network simulator that allows simulation of complex networks.
Unity - The multiplatform game creation tools for everyone.
ns-3 - a discrete-event network simulator for internet systems
Godot Engine - Feature-packed 2D and 3D open source game engine.
NetSim - NetSim software was created to simulate various Cisco systems. Cisco software is known around the world as being one of the best network, routing and switch systems for businesses and private use. Read more about NetSim.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.