Comparing your screenshots to what I'm getting, I think somethings wrong with what I see. All I see is a black background, gray circle and an orange circle getting bigger, then smaller, bigger, then smaller(orange cirlce only).... I tried pressing all the controls you mentioned, but the only thing I can do is move the gray cirle within a certain area. If you used pixel shader, it might explain it since my computer doesn't support pixel shader 2 (I think, it has problems with it anyway).
Anyway, here are my suggestions though I can't play your game(sorry if they are already included in your game):
Menu with following options
-Instructions or Tutorial
-Quit(maybe not necessary since they can click x in corner?)
Play Game could go to a submenu screen where the player could pick a level with the terrain, graphics, difficulty, etc. that they wanted.
You could give a short tutorial in the game to explain all the controls and some objects in the game.
Obstacles and objects that will fall and kill the miner if he/she removes blocks from under it.
Tunnels collapse after a certain amount of time has passed.
Supports that extend the amount of time before a tunnel collapses, possibly infinently depending on the level of difficulty.
On easy difficulty, make adaptable difficulty. For example, if a person gets killed so many times within a certain time period by aliens, decrease the stats of the aliens (Those were aliens in your screen shot, right?).
Just giving you some ideas, I hope they help.