Nitro GP is a custom track distribution created by Narceja. It adds many custom cups and retro cups, as well as a new UI and features.
This is the source code for the distribution using the Pulsar engine by MelgMKW, based on the work of Kamek by Treeki. Most of the edited code comes from Yosh's Track Pack DX's source code, which itself uses the OptPack source code as a base.