Neat Submission.
Lighting is very well implemented. Gives the game a nice mood, and really enhances the simple shapes-based art style chosen. The glowing gold that acts as another source of income is a nice touch.
Sound design in excellent. Dripping effect in the background is subtle, but really adds to the feel of the game. Pistol sound is nice too, nice that it has a slight echo.
For improvements, definitely need automatic fire. My finger hurts, and the lack of autofire was ultimately what stopped me from playing further. A way to get back to the surface faster would be appretiated too.
Well done!