The oldest crpg I ever played was called advent, because the Vax computers could only use 6 characters for file names and so the people who ported it couldn’t use the actual name “adventure.” It was basically the same as the game infocom shipped as Zork.

Apparently the original implementation was on the PDP-10 in 1976. There might have been a couple other games that predated it by a year or two, but adventure was the big one in my opinion because it led (eventually) to the creation of the infocom text based game engine and a whole line of games ranging from hitchhiker’s guide to the galaxy to leather goddesses of Phobos.