Firewatch - Lock Box Cache Widget is a little interactive fan-art widget inspired by Campo Santo's game Firewatch. Though the actual style of the widget is a little different than the one in the game, the core mechanic is the same. Henry (the main character in the game) interacts with it as you progress through the game.
If you played the game, you already know the code to unlock it. If you haven't played, take a generous hint from the image below before clicking Play with the Widget. You can use arrow keys or clicks/taps to interact.