GarlicSim is a platform for writing, running and analyzing simulations. It is general enough to handle any kind of simulation: Physics, game theory, epidemic spread, electronics, etc.
When you're writing a simulation, about 90% of the code you write is boilerplate; Code that isn't directly related to the phenomenon you're simulating, but is necessary for your simulation to work. The aim of GarlicSim is to write that 90% of the code once and for all, and to do it well, so you could concentrate on the important 10%.
GarlicSim defines a new format for simulations. It's called a simulation package, and often abbreviated as simpack. For example, say you are interested in simulating the interaction of hurricane storms. It is up to you to write a simpack for this type of simulation. The simpack is simply a Python package which defines a few special functions according to the GarlicSim simpack API, the most important function being the step function.
The beauty is that since so many simulation types can fit into this mold of a simpack, the tools that GarlicSim provides can be used across all of these different domains. Once you plug your own simpack into GarlicSim, you're ready to roll. All the tools that GarlicSim provides will work with your simulation.