A now-legendary games company, active from 1979 to 1989, that commercialized the MDL parser technology used for Zork to produce a line of text adventure games that remain favorites among hackers. Infocom's games were intelligent, funny, witty, erudite, irreverent, challenging, satirical, and most thoroughly hackish in spirit. The physical game packages from Infocom are now prized collector's items. After being acquired by Activision in 1989 they did a few more "modern" (e.g. graphics-intensive) games which were less successful than reissues of their classics.
The software, thankfully, is still extant; Infocom games were written in a kind of P-code and distributed with a P-code interpreter core, and not only open-source emulators for that interpreter but an actual compiler as well have been written to permit the P-code to be run on platforms the games never originally graced. In fact, new games written in this P-code are still being written. There is a home page at http://www.csd.uwo.ca/Infocom/, and it is even possible to play these games in your browser if it is Java-capable.