james_davis_nicoll points out another change that may be a response to the OGL thing - Chaosium have just dropped the price of the 400-page PDF version of Basic Role Playing - the percentage-based system behind all of their early games including Runequest, Superworld, Call of Cthulhu etc. - to 99 cents for the next ten days.
https://www.drivethrurpg.com/product/24384/Basic-Roleplaying
There's actually two different versions with different file sizes, not quite sure why yet.