In the Zone there is missing footing.s and there is also screen.s but is incomplete and contains some invalid chars. I use DiskSalv on some RollingThunder.adf to check if there is something interesting and I found a bunch of files. Whole archiwum is in The Zone.
As I remember file Sound.s is from Atari ST version. I'm not sure but there were differences between resourced game and sources.
The Rolling Thunder is example how to write very slow game. About 5 fps. For fun I speed up title of game to 50 fps with blitter help but it still looks so ugly.
But there is one positive thing. So many things which can be optimized.
; a0 - datas address
;save start of datas
Above two lines of code eat 24 cycles and 6 bytes in relocation table. With one modification
will take 20 cycles and no bytes in relocation table. There is so many such places and I even thought about tutorial: how to speed up slow game on example: Rolling Thunder.