This GitHub page hosts the Spore ModAPI development kit, used to create Spore mods with C++. To use those mods, you need the ModAPI Launcher and Installers.
The Spore ModAPI SDK allows you to create C++ mods for Spore. These mods are compiled into .dll files,
that can then be used by the ModAPI Launcher Kit to inject them into Spore.
The documentation of the SDK is available here: https://emd4600.github.io/Spore-ModAPI/
Instructions about download, installation and updating can be found in this tutorial.
The source code can be found in this GitHub repository. It also includes the source code of 3 real mods made with the ModAPI SDK: