Frotz

[*Warning* Playing Frotz involves reading, thinking, and typing. If you just want to blow stuff up, this is not the app for you!]
Burned out on all the new-fangled graphics and dazzling eye candy on your shiny new iPhone or iPad? Nostalgic for a simpler time? Then take advantage of those crisp high-resolution fonts to relive the glory days of the Great Underground Empire, or play any of hundreds of great works from the Interactive Fiction archive.
Frotz lets you play hundreds of free works of Interactive Fiction (a.k.a. text adventure games) on your iPhone or iPad.
Frotz plays titles written in the Z-Machine format (which was invented by Infocom and was used to produce classic text adventures from the 80s such as the Zork Trilogy, Hitchhiker's Guide to the Galaxy, and Trinity), as well as glulx and TADS formats.
In the past couple of decades, text adventures have experienced a renaissance of sorts due to the efforts of a diverse Internet community of talented interactive fiction writers and fans. Many of these games are written using the same engine that powered Infocom's titles, thanks to the Inform compiler and authoring system created by Graham Nelson.
NOTE! If you have suggestions for improving Frotz or encounter bugs, please go to the support link and report them.
Frotz for iOS - Interactive Fiction at Your Fingertips