Orthanc

This game is an Android version of "Orthanc", one of the first graphic dungeon crawl role-playing games developed for the University of Illinois Urbana-Champaign's PLATO computer in the 1970s. The original was played on a PLATO terminal with a keyboard. (The PLATO version of "Orthanc" was inspired by "pedit5", which you can learn more about in Wikipedia.) There is no sound. This implementation uses the touchscreen for all gameplay, but if you have a keyboard attached to your device you can use keys for some actions.

Orthanc is easy to start but hard to put down.