"I don't think interactive fiction programs will ever replace reading novels," says Spencer Steere, a spokeswoman for Infocom, the Cambridge company that has created and cornered that market, "but people have started to recognize it as a popular form of entertainment."

According to Steere, 37 percent of the interactive fiction audience is under age 20. More than three quarters are male and are generally well read -- 43 percent read 10 or more books every six months.

Current figures from Softsel, the nation's largest software distributor, place these interactive fiction titles on its Top 20 hotlist of all recreational software (all are available for IBM, Apple, Atari and Commodore and range in price from $29.95 to $49.95):

Hitchhiker's Guide to the Galaxy (Softsel's No. 8). In its first year, Infocom is topping all interactive fiction sales with this program, based on Douglas Adams' book of the same title. You assist the hapless protagonist Arthur Dent, who uses an electronic thumb to hitch rides on passing spaceships. Interaction with a sense of humor.

The Zork Trilogy (Softsel's No. 14). You've tumbled over a cliff but landed safely on a small ridge where you find a locked treasure chest. Further descent to the seaside below would be treacherous -- perhaps deadly. But wait! From above, a mischievous voice promises to lower a rope and pull you up if you first send up the treasure chest. Do you do it? Wisdom and courage are tested in "Zork III," the third of Infocom's all-time, best-selling adventure fantasy trilogy, which many dealers say has started more people on the habitual path of interactive fiction since its release in 1979 than any other program. In "Zork I," you try to discover 20 treasures hidden amid the perils and predicaments of the Great Underground Empire. "Zork II" pits you against the powerful Wizard of Frobozz.

*The Hobbit (Softsel's No. 15). The latest challenge to Infocom's near-lock on the interactive fiction market is a software version of J.R.R. Tolkien's popular masterpiece of fantasy, produced by the Massachusetts firm Addison-Wesley. The action parallels the Tolkien storyline so closely that the book is included in the package and serves as "the ultimate hint book for the game," according to a company spokesman. Color graphics are optional and experienced players often grapple with text only. "We get lots of calls from people lost in the Goblin's Hall or who can't get out of the Elfin King's Wine Cellar," says the Addison-Wesley spokesman. "It is rather complex and not meant for people below high school age."

*A Mind Forever Voyaging (Softsel's No. 17). Released in the fall by Infocom, this science fiction program is more literary and difficult, with a larger interactive vocabulary than the other Infocom programs. It kicks off when you are told the "devastating truth" that you are in fact a computer that has been raised for 20 years as human to think like a human. Your mission is to explore various simulations of the future to determine long-term effects that could change the course of mankind. Requires 128 K.

*Wishbringer (Softsel's No. 18). A visit to the old magic shop turns the small seaside town sinister when The Evil One kidnaps the shop owner's cat. With seven wishes from the magician and the Wishbringer's Stone, you set out to rescue the cat.

Washington metropolitan software stores regularly mention two other Infocom games that sell well here. Deadline, a locked-door murder mystery, provides you with lab reports, police records, suspect dossiers and evidence to solve the case -- in 12 hours. And Suspect starts with a murder at a socialite Halloween party in Maryland, and you are the suspect. You have to solve the crime to get yourself off the hook.