I can't recall there ever having been a TTRPG specifically tied to the Mad Max property. Much because, I suspect, the "lore" of the Mad Max setting isn't all that opaque or intricate, and there already was Aftermath, Gamma World, Morrow Project, the original T2k, Danger International, so on, so forth, that people could use to play in "that" setting, or one similar enough to scratch that post-apocalyptic itch.
It is only nowadays that having the game explicitly carry the brand of the setting/property that we play in has become an end unto itself, or so it seems. Back in the early days — even though there was a bunch of licensed games — most often, we just had to "make do and mend"...