Seems to be a very basic social network based on concepts from an old protocol called finger. This website seems to replicate it as a bit of nostalgia.
As you might know, finger is an old protocol (actively used well before my time) which in essence showed information about the users on a server running a finger daemon (usually a Unix-like system).
As I understand it, when you queried for information about a user, a piece of the information you got back would be the contents of a ".plan" file in the user's home directory.
In this file a user could provide what we now call "status updates", which would then be promulgated by finger. You might have put your location, or what you were working on.
To avoid doubt, you can do all of this on the website and don't need to actually use the finger protocol at all. But for true nostalgia you'll need to use the finger command - which works!
.plan is the historic unix equivalent of todays status on social media.
you would write your status (or what you plan to do or whatever) into a .plan file in your home directory,
and you could use the finger command to query the contents of that .plan file from other users on the machine. or on any other accessible machine.
plan.cat appears to be an attempt to make that feature accessible through the web, complete with the ability to create an account and add your own .plan file.
not what i would go for. i would much rather prefer something similar that i put on my own webpage. (well, technically, all it would take is to agree on a standard url like https://my.home.page/plan or something like that.
