Dear Esther is a milestone in the development of the modern exploration game, often pejoratively referred to as "walking simulators". Originally a Half-Life 2 mod, Dear Esther has players wander a lonely island as a story unfolds via the landmarks they encounter. It can be completed in an hour. Its studio, The Chinese Room, went on to make Everybody's Gone to the Rapture, though before that, it worked on the Amnesia spin-off A Machine for Pigs—the latter a kind of blueprint for the modern pacifist horror game (see also Outlast, Visage).
It's definitely worth playing if you're interested in how games have evolved so far this century, and now's a better time than ever, because it's currently free on Steam. Specifically, Dear Esther: Landmark Edition is free, the 2017 Unity Engine remake which not only looks a whole lot better, but also has improved audio and a Directors' Commentary mode.
All the way back in 2012 we reviewed the original Dear Esther, which was something of a phenomenon at the time. "A trip through a brilliantly conceived landscape that rewards attentive engagement with a moving story," Chris Thursten wrote.
The Chinese Room is releasing Little Orpheus on PC next month. Originally released on Apple Arcade in 2020, it's a marked departure for the studio, moving away from first-person exploration in favour of a sidescrolling adventure reminiscent of Another World.