AFAIK this is the first time anyone has finished this in one sitting: (18:57:41)
The idea has existed for a while though: finish the game without equipping any weapon, armor, or shield, or extras like the Fighter's Ring or Dragon Scale.
The question, of course, is: what about RNG manipulation? It'll probably need split categories just like Any%, because I don't see why someone couldn't route the game manipulated without equipment (even if it would be quite different from the Any% run).
Having run rMME for a while now and submitting two runs, I decided tonight to look the game up on SDA. It would seem, from what they have, that the two releases of realMyst - the original from 2000 and the Masterpiece Edition from 2014 - run on totally different engines and have MUCH different movement mechanics. In particular, the original has a glitch which allows for running at twice the normal speed; I tried duplicating this in the ME to no avail. A few other things also run at different speeds or present themselves at different angles, and although I haven't played the original, it seems that the mechanic of switching between movement and interaction mode works a bit differently, too. Because of all this, the run stored at SDA is 28:20, over seven minutes shorter than my PB of Masterpiece, even though his movement through the ages is far less precise and he turned on all the marker switches at the end of the run (!?).
I would recommend creating new categories for rMME and moving my runs there.