Background: I am currently working on a warefare simulation where all the objects within a 3D world are controlled by the worlds AI. Each player owns his own 'General' and sets goals for that general as well as some behavior parameters for the 'Commanders' under that general. The individual units receive orders from their commanders and behave accordingly. I would like this to be based on a central server where players can log in and watch the simulation in real-time as well as issue new goals. Problem: Does anyone know of any engines or middleware that can handle collision detection (physical as well as spheres of influence) and pathfinding that won't add massive overhead on the server. I would like to have my AI scripts issue movement commands or attack commands to those units and then wait for a triggered response. I would also like to have the client side of this setup be able to view the simulation in a 'pretty' 3D rendering. I currently have the simulation working without pathfinding or terrain (using a flat surface where objects just pass through each other) through python and a MySQL table for test purposes, but I would like to move away from that. Also, some sort of scalability would be nice. Any help or advice would be greatly appreciated. Thanks in advance. P.S. I wasn't sure if this was the right forum so if this needs moved to somewhere else, please do.