The six winning entries from the 1995 IF competition [What sort of events does the IF community do?: 2.6] were published by Activision on their CD-ROM release, "Masterpieces of Infocom" (July 1996), which has sold surprisingly well. Activision also uses the Inform authoring system as a prototyping tool for some of their large graphical games (such as "Zork: Grand Inquisitor"), and used an Inform Zork game (by G. Kevin "Whizzard" Wilson, Marc Blank and Mike Berlyn) as a promotion for Z:GI.
Specifically, the readership of the two rec.*.int-fiction newsgroups make up a faithful audience. Popular games such as "Curses" have been played by quite possibly thousands of people worldwide. In this specific case, the game has been downloaded at least 2000 times from two sites (more from other sites, but figures are unavailable), published on at least 4 CDs (probably more without the author's permission) and as a cover disc of two magazines with circulation in the 10000s, and included in commercial packages.