The simplest way to use Improviz is by getting one of the pre-built binaries. If you want to make deeper changes, or contribute to development, then it will be necessary to build the project locally yourself.
The main repository contains all the code and can be found on GitHub.
Improviz uses the stack tool to build the project. Once you have that installed, it should be possible to just browse to the cloned repository directory, and run
stack buildImproviz can be run directly from the project folder with stack.
stack exec improvizThis should present you with the white starting window. The improviz.yaml file in the root folder of the project will be loaded as a configuration file.
You can install the fully built binary onto your system so it's not necessary to run it from the project folder. stack install will build Improviz and install it to the stack local-bin-path which by default on OSX is ~/.local/bin. (I'm unsure what it is on Linux or Windows).
With the installed folder added to your path, you should just be able to run improviz from the command line.
Improviz has a suite of tests that can be run using stack test