The Famous Five - BRG files

[SuperFlomm]

The only thing I can imagine they contain would be placement data for the interactive sprites, and not any graphic data.

That must be it.

alpha masks, telling the game which part of the SMKs to display and which parts to make transparent.

I guess they use a greenscreen to tell the game which part is transparent. Else I can't explain why every background has the same green color.
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