Is there a way, in a predefined square area of the screen (or even circular area), to modify the colors such that it is almost like a light being shined into an otherwise "dark" area. I was thinking to make all light grey, white and all dark grey, black, but I'm not sure if that would be an accurate effect.

Anyone any ideas?

Assuming you already have a pair of buffers for grayscale, one thing you could do is decrease the lightness one level for all pixels r1 <= radius < r2 pixels from the center (white -> light gray, light gray -> dark gray, dark gray -> black), decrease it two levels for r2 < radius <= r3 (white -> dark gray, everything else to black), then fill with black outside radius r3. That would not be smooth, though, so you'd probably want to consider some dithering. You could pre-define a very nice-looking dithered mask if you have 768 bytes free for it in your program.

I actually might have 768 bytes. Depends on the total size of the program without it. The data section as of now looks to be in the ballpark of 5 kB, so I don't suppose its too bad.

Btw, how is rendering a masked sprite different to rendering a normal sprite. I know that in concept, its limited to three-level greyscale, with the white configuration actually being transparent, but when I had a look at how Axe handles it, my brain exploded.

bump