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When it comes to Whitebox-based materials, James M. Spahn is definitely the first name that comes to mind. After all, he's penned White Star, White Box Compendium, White Box Omnibus, and Untold Adventures - among other things.
The Hero's Journey is a game unsurprisingly also based on Swords & Wizardry Whitebox - but note that even though the base is clearly recognisable, the end result isn't readily compatible with it (as such, it's in similar shoes to Helvéczia and Exemplars & Eidelons).
Note that this review is concerned about the 2nd edition of the game (although I have written a shorter piece about the original (released in 2016) on EN World).