Call of Cthulhu: Darkness Within is an adventure game inspired by the writings of H. P. Lovecraft developed for mobile phones. The game takes place in Cairo in the 1930s. The protagonist is a student of a professor who gets a letter from his teacher asking him to come to Cairo ASAP as he has uncovered something extraordinary and fears that he is in danger. Balthazar Carter arrives only to find that his professor had gone insane and the expedition is put on hold. The new director is known to be interested in the occult and doesn't take kindly to Balthazar's curiosity. Being an expert in old Religions, players will need to help Balthazar uncover what happened to the professor, what was the find as well as the mysteries of an ancient religion which worships the god Cthulhu.

The game plays out as a point-and-click adventure, but instead of a mouse interface, players control the protagonist directly with him walking to the direction key players have pressed. Players are hinted when they're close to usable objects or people and can trigger a menu where they can choose what they want to do with the objects. Players can pick up and use items and during their adventures they will see a lot of cutscenes of what's going on in the city. Players switch to a top-down view when traveling through the city. The buildings players have access to are indicated with an icon.