If you haven’t use flixel-gdx before, please use the setup-gui to setup your project. If you download the zip, you’ll have to manually setup your projects. Check this wiki page “Using the GUI” for more information.
Now and then we release a stable version with a number. The zip file contains flixel-gdx, libgdx and 3rd party libraries. Latest Release
Nighty builds are released every time if something got changed in the Git repository. You can use the nightlies if you want the latest features or bug fixes. Nightlies are usually very stable. Latest Nightly Build
The flixel-gdx source code is hosted on GitHub. Fork, star and contribute to our project! Github Repository