Kinda wasted yesterday. Hopefully today is better.

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The idea
Draw the background over a set of 4 giant 512x512 sprites, (remembering that the "screen" is only 426x256, so you've a decent amount of scrolling) then draw destruction over the sprite, (colour 0,0,0 with alpha 0) and use SmileBASIC's pixel-perfect sprite collision to collide with said sprite-background.

Possible Usage
Worms, Gravity Force, things that require collision with a none-tile-based background.

Result
In order for any drawn 0,0,0 pixels (eg exploded backgrounds!) to become "none-colliding" and transparent, you need to use the "GUpdate" command after drawing to the sprite layer. This takes what you've changed, updates the pixel-perfect collision stuff, and also the way it's drawn so that the transparency works.

This does kinda work, but it seems to have a frame-delay when in use. As in, you draw the change on frame A, but the changes onscreen don't happen until Frame B. And, I might be wrong, but I don't think the actual collisions work until Frame C.

As such, the entire game wouldn't be realtime enough to be functional in a lot of scenarios.

It COULD be used in plenty of other places, but for the game I was looking forward to doing, it really isn't workable at all.
Shame..

Time to come up with a different game, then..
Hmm..