This text adventure transports the player deep into the South American jungles, in the footsteps of renowned archaeologist Dr. Paul Jamison - a friend who had disappeared under unknown circumstances on his quest to unearth the ancient secrets of the Inca Empire. Spurred on by a mysterious note from Jamison, and by the sole item he had left you (a golden brooch), you set sail to Peru in search of the lost city of Tumbrez and its fabled treasures. You soon find yourself beset by a pair of crooks who are on a treasure-hunt of their own.

Powered by the Story Teller engine also used in The Holy Grail, Inca interprets simple textual commands and provides the player with multiple save slots. A real-time element is also present: certain events are timed, and swift reaction will often be required to avoid unpleasant situations (such as being seized by the antagonsistic duo, or a variety of nasty deaths).