The money quote, from George Ditomassi, Milton Bradley’s Senior VP for Sales:
We wanted a game that would cater to a market that already existed—Dungeons and Dragons… Dark Tower will not attract the Dungeons and Dragons aficionado. But that’s a small, intense market. We wanted the next level down—people who had heard about D&D but who didn’t want to be Dungeons and Dragons freaks. [Italics mine]
The article is from September 27, 1981. More Dark Tower here.
2 Warps to Neptune 
1981-82…I still remember the day I went to my friend’s house, and, instead of us making a beeline for his Atari, he pulled out the Dark Tower game. Although he did have his share of D&D manuals, figurines, etc., he wasn’t a D&D freak (lol). We had some fun playing that game a few times, but it was no comparison to video games and arcades.
I may have mentioned this before, but someone made a virtual Flash version of Dark Tower you could play online:
http://hofle.com/darktower/DarkTower.swf
By no means as cool as the original obviously, but it does give a good glimpse of the blips and bleeps the game used. Lol. I specifically remember Dark Tower being my introduction to the word “Haggle.”