Nice art and way to use the theme. The music is nice too, although it would have been nice to also have sound effects for things like picking up the artifacts. A crosshair to see where I was clicking would have been nice (though I imagine some players would prefer not to have a crosshair, so maybe it should have been optional. When I got lucky I could pick up three artifacts, or maybe you have to be very close to them, in which case changing the appearance of the crosshair so that I wouldn't have to click around blindly would have helped.
The music fit the gameplay and maybe it can even help players know how much time is left. And the black-and-white art seems appropriate for a game about stealing stuff and not getting caught.
One thing I could have wanted (not that I managed to get that right myself) is restarting without having to reload the page.