See the attached file - I have added five bytes to the 'Set Willy's attributes' routine, immediately after the ADD HL, DE command which - prior to the code changes - used to be at #9614.
The five bytes in question are:
7C - LD A, H
FE 5E - CP #5E
30 07 - JR NC 07
The effect of this intervention is to disable the 'bug/quirky feature' that causes Willy to die if he tries to fall off the bottom of a screen which has a Fire cell located above him at the top of the screen.
The starting point in the file is set to A Bit of Tree, and I have inserted a Fire cell nearby to demonstrate that falling onto a Fire cell within a screen still kills Willy as per usual.
However, if you jump Willy up to the screen above, Under the Roof, and then walk rightwards off the platform that he lands on, you will see that he falls off the bottom of Under the Roof without being killed by the Fire cells at the top of that screen due to the 'bug' - only to land (repeatedly!) onto the newly-inserted Fire cell in A Bit of Tree!
Edited by IRF, 23 June 2016 - 12:38 AM.