Take one of the walks (Voyages into deep time) - more to download soon - and try to survive in the planets past environments by building a leading score. Your score is built by answering tasks, dealing with unpredictable threats and maintaining virtual supplies of oxygen and water. Your fuel is your devices battery charge.

The game is designed to be played by actually going to the physical location of one of the Voyages and taking the route the app will give you. You can look at, but only answer the tasks and meet the threats by actually being there! Attempts to cheat the app about your location will wreck your score.