A multi-user application system environment engine has an application system that, in turn, includes a simulation engine and a virtualized software environment. The simulation engine runs on top of the virtualized software environment and is configured to operate as a server. The simulation engine includes a declaration processor, a scene tree object manager, and a server listener, which processes any received change message by causing the declaration processor to transform each change declaration embedded in such change message into a corresponding change in an instantiated scene tree. The sever listener executes a synchronization process that records each change declaration in a declaration repository.