The save file is located on windows by default at: windows ~ C:\Users\USER\AppData\Local\NovaDrift\ (may have to show hidden folders to see) on windows (other platforms do not have a singular save location and must be checked depending on the default save location for macOS and linux - the latter depends on whether Proton or WINE is being used). The file name is save.ini

Open the save file with a relevant program (e.g. notepad) and type ctrl + f (or whatever relevant search function that program uses) and search for "accountLevel". Set the level to "64.000000" in order to unlock everything. Note that account level 8 is required to unlock Enemy territory (in order to skip the first 11 waves - though this is not required for any category), account level 50 is required to unlock Annihilation mode, and account level 64 is required to unlock the Ataraxia supermod (which is commonly taken in speedruns - though not mandatory).