Recommendations by Xervosh (San Jose, Northern California)
The ones I personally enjoyed, and on that admittedly flawed basis, extrapolate you might enjoy the most as well. Presented in chronological order of release.
1. Zork I by Marc Blank and Dave Lebling (1980) Average member rating: (215 ratings)
Xervosh says:
Surprisingly challenging in many respects. I still feel pride in the fact I figured out how to enter Hades, and to acquire the Pot o' Gold, entirely on my own. Two mazes are a pain in the ass, however.
2. Zork II by Dave Lebling, Marc Blank (1981) Average member rating: (95 ratings)
Xervosh says:
A worthy, somewhat more challenging sequel. No actual maze per se, but a very annoying, maze-like puzzle does mar the game.
3. Enchanter by Marc Blank, Dave Lebling (1983) Average member rating: (108 ratings)
Xervosh says:
While perhaps not as aesthetically compelling as the first two Zork games, its hugely enjoyable, and I really can't think of anything in particular that's wrong with it. Somewhat less difficult than most Infocom games.
4. Planetfall by Steve Meretzky (1983) Average member rating: (118 ratings)
Xervosh says:
A magnificent game, loads of fun. Perhaps Infocom's best. The robot Floyd is certainly the best NPC in the commercial IF era. The ending bothers some people, but it wouldn't have bothered them, had the game not been so well made in the first place.
5. The Lurking Horror by Dave Lebling (1987) Average member rating: (92 ratings)
Xervosh says:
Amusing, pseudo-Lovecraftian collegiate horror romp. Never managed to solve this one (yet), but I got far enough with it to heartily endorse it.
6. Plundered Hearts by Amy Briggs (1987) Average member rating: (64 ratings)
Xervosh says:
I'm taking a little risk by including this one, as I'm fairly new to it, and thus haven't gotten very far as yet, but from what I can see, its enormously promising. I feel confident in recommending this highly influential game (prior to Plundered Hearts, PCs were all just generic adventurers with little or no innate qualities; this game makes you a specific person - an attractive woman, no less - and limits your actions based on what is socially conceivable for a person in your position). Plus, the whole pirate motif is a great IF setting.