The alt2 is the deobfuscated version; the alt one is the one with the
ability to slow down/speed up the fluid and control the gravity factor,
the pressure factor and/or the viscosity factor.
The alt version no longer imposes a lower limit on the factors because
doing so prevents the ability to define them to 'I' which the author
noted is a functional difference.
The alt versions let one control how long to sleep between writes as in
modern systems it goes pretty fast. There are two, one for the colour
version that was added by Yusuke at the request of the judges and one
for the original. But the one for the original is called endoh1.alt2.c
as Yusuke provided endoh1.alt.c as a deobfuscated version.
The new alt versions let one only redefine certain macros should they
choose but they can define them all or not define them all because of
the #ifndef..#endif guards. These macros include the sleep time (S) as
well as the others that Yusuke suggested one might want to change.
The README.md file has been format/typo checked.
Cody Boone Ferguson