Flutter (opens in new tab) is a game where you walk in a line, from left to right, so I suppose it doesn't fit neatly into the adventure game label I've laid on it. There are no puzzles, and it lasts 5-10 minutes, but you get a full blast of a dreamy sci-fi story for that brief duration.
Inspired by the band Lightbath, who sound pleasant enough from the track of theirs I've heard in the game, Flutter is set in a world where all the birds have disappeared. I think. (It's a bit vague.) To say any more would pretty much tell you everything, so if you like scrumptious pixel art and washy indie music, you should download it to experience it for yourself.
If Flutter was a short story, it would be a couple of pages long at most, but there is of course a place for such micro-stories. Just as there's a place for brief games like this one, that serve up a slice of mood, of atmosphere and an unfamiliar world.
For more great free experiences, check out our roundup of the best free PC games.