iPhone gaming just got a shot in the arm with the release of Frotz, an interactive fiction (aka text adventure) app that's free to download. With it, iPhone owners can while away the hours with dozens of text-only games, getting lamps, facing north, being frozen by wizards... all that fun stuff! That means you have another opportunity to play Zork, Trinity or The Hitchhiker's Guide to the Galaxy should the only high-def visuals you require be ultra smooth fonts.
Frotz, available via the App Store right now, comes with "several" built-in, public domain games. It also provides easy access to the Interactive Fiction Database, giving you nearly endless options for replayability. Get on it!