Deadly Towers was developed by Irem and published in September 1987 by Broderbund for the NES. Finding an actual copy of the game isn't terribly difficult at a decent used video game store, and the ROM is complete, functional, and readily available. This is all assuming that you want to subject yourself to the pure screaming pain, but, hey, different strokes for different folks. The packaging is very bland, with only a purple-blue background and "Deadly Towers" displayed prominently.
Deadly Towers does have some minor historical significance. It was a victim of Nintendo's institutional censorship, as the original title of the game was "Hell's Bells." (The premise of the game is that Prince Myer, the hero, has to climb to the top of each of the massive castle's towers to obliterate each of the bells, so that the shield defending Rubas, the obligatory uberpowerful villain, is lowered, and he can be defeated.) Of course, numerous references to the Devil made it into the manual, similar to the failure of the censorship in Bionic Commando.
In addition, it was one of the few adventure-RPG games to use passwords instead of battery-backup saves, a crime inexcusable after the release of the Legend of Zelda. The game became infamous for the fact that by inverting the first two letters of the password could change you from the worst equipment in the game to the best, rendering the shops and money utterly pointless.
The game's sparse text was also a low-quality endeavor. A quote of some renown from the manual is the description of the small sword: You start the game with this sword. It is so weak, you feel lonely (you have no confidence in this sword).
This game is a true example of shovelware, and the only possible reason to own it would be for the same reason poets owned human skulls: to remind them that all human endeavor can be reduced to such.
Sources: gamefaqs.com, Electronic Games Monthly, and, curiously, seanbaby.com