Editing parts of objects (please answer)

I don't know if this is possible, but I was wondering this for a while... How would you make a like, flashlight, digging, fog of war sort of thing? you know, when you dig it goes though the dirt, or in otherwords the object, but it has to get rid of part of the object but not the whole thing. I don't want to make a billion pixel-sized objects. If that makes any sense, please help me out with this. If it doesn't, then tell me. If you don't know, please tell me.

Thanks,
Skeets

For permanent removal (digging), either use square pieces that overlap slightly (with nice uneven edges), and destroy the ones you want. It's not pixel perfect, but it looks really good. The newest Kirby game on the DS uses this. Worms for the original game-boy used a similar thing for the explosions cutting holes in the landscape.

You could do something similar for fog of war.

Or use the overlay object, and simply load your level into it as an image, and then erase bits.

For a flashlight, there's a great ink-effect trick: Use a black background, with the flashlight (pure white) UNDER all the other objects, and have every object set to render using "and". You have to be careful though, because objects don't overlap friendly like this.
There's also an opposite trick, using a full-screen black image with the "flashlight" cut out :)

Thanks for the tips! I will try that!