This game was exported in Flash and, as you probably know, Flash has been discontinued. As such, I can only provide access to the source code and the
.swf file at the moment.
If you happen to have an ancient computer that still runs Flash in the browser, or a copy of the Adobe Flash Standalone Player, you should be able to run the game.
Durations has been featured on Kill Screen, Kotaku’s Watchlist, IndieGames.com, and Joystiq. It has also, rather impressively, been reviewed from inside itself. And here is a nice piece of writing about Durations and Mountain from Alex David Jones.