DoD actually didn't run on the Model 100/200 series, which was purely a writing machine. You're probably thinking of the TRS-80 Color Computer 2, aka the CoCo 2 or Trash-80. Dungeons of Daggorath was (in my opinion) the best game for the CoCo 2 and one of the earliest dungeon crawler games.
It's a real shame Dungeons of Daggorath was replaced in the movie version of Ready Player One. Adventure, with its Easter egg, wasn't a bad replacement but the CoCo got so little mainstream love in its day that it would have been nice to see it on the big screen.