Modelling and Simulation 

Modelling and Simulations are broad categories of tools. There are close relationships between these and tools/ methods for Gaming and full scale tests. Basically one can do modelling and simulations without a computer just as well as gaming can be done without.

There are several types of computerized modelling and simulation tools. The one with most focus in the following is System Dynamics that grew out of former work on Numerical Methods, and is  contributed to Jay Forester at MIT. 

But there are many others like event oriented systems (coming from procedural software programming) and agent systems (coming from object oriented programming). And there is a huge group of systems related to geometry and design.

Some tools are very detail oriented and demands that users write code, and others have graphic as the main user interface.

To read more on tool that includes Agent Based, Discret Event, and System Dynamic methods:  se

Modelling and simulation (wikipedia definitions)

AnyLogic (free modelling and simulation tool for students) 

ISEE- Ithink -   Stella Professional Stella Architect

Stella Online (free version)

InsightMaker (free modelling and simulation tool)

System Thinking.  

System Dynamics 

System Thinking World

Vensim (free for students)