Note that there are numerous versions and forks of Colossal Cave Adventure, several of which are called "the original". For the most complete known family tree (actually a DAG in a few places), with links, see:

https://mipmip.org/advfamily/advfamily.html

Some important versions: WOOD0350 (added most of the feature we know about; allegedly there was an early 250-point version in the wild but it's poorly documented), GILL0350 (C port, made it into bsdgames among others), WOOD0430 (the final version by him, what open-adventure is based on). But several other lineages are also well known (you can see .

The link submitted is a bit of a mess. src/ contains multiple versions of CROW0000 (which had been thought lost prior to 2005). But the various images are for other versions, and I haven't checked the binaries.

If you're interested in hacking your own version of adventure, the best by technical measures (reproducibility, sane file format, etc.) is:

https://gitlab.com/esr/open-adventure

(But the major change of file format does mean it becomes difficult to apply changes from other members of the Adventure family. This is also a problem for some others though!)