The Mammoth: A Cave Painting

A short, free, interactive scroller in a phenomenal artstyle, well worth a look.
The Mammoth is a great little piece of storytelling in the confines of a simple 2D control scheme and an amazing cave-art aesthetic which is served beautifully. What could easily have been made as a four-minute YouTube video, and without wishing to spoil the story’s content, instead gains a certain degree of emotional investment in having the play guide the titular mammoth.
This game does include one Steam Achievement which is awarded at the end of the piece, which had become something of a joke as an easy +1 to one’s Achievement Counter, but at least that has attracted more people in to experience this journey firsthand.