Very trippy. Makes you think what the actual hell is going on.
City Lights by Ian MacLarty
Click on the game to let it grab your mouse, then use WASD to move and the mouse to look. If you're using Chrome or Firefox you can press Alt-Enter to toggle fullscreen mode.
The game should work in recent versions of Chrome, Firefox and Safari. It works in IE11 as well, but there is no audio.