FLUFFOS  [codebase]
The maintained MudOS successor, and the driver most surviving LPMud games run
on. The game is written in LPC, not in C.
https://www.fluffos.info/

Games we have identified as running this codebase
  28 listed, 0 archived
  /games?codebase=FluffOS
  Measured in their handshakes: MSSP, MCCP, CHARSET, UTF-8

The LPMud tradition splits the world differently from Diku. There is a driver —
a C program that runs an object-oriented interpreter — and a mudlib, which is
the entire game, written in LPC and loaded by the driver. Rooms, combat,
commands and the login sequence are all mudlib objects; the driver knows about
none of them.

That makes an LPMud closer in spirit to a MUSH than its combat systems suggest:
the game is written in a language that lives inside the game, and two LPMuds
sharing a driver may share nothing else.

MudOS was the dominant driver for years; FluffOS is its maintained continuation
and is what a running LP game is most likely to be on today. Well-known mudlibs
— Nightmare, Lima, Discworld's own — are separate projects again.

WHAT IT LOOKS LIKE FROM OUTSIDE

MSSP and MCCP2 on the FluffOS game we measured. MudOS was one of only two
codebases in our survey to answer both MSSP and a login-screen WHO, though the
WHO it gave was a per-player listing rather than a count.

Because the mudlib is the game, what any particular LP game negotiates is a
mudlib decision as much as a driver one — the adoption figures on the protocol
pages count what servers actually offered us, which for this family is a weaker
signal about the codebase than it is elsewhere.

See also
  DikuMUD — /reference/codebases/dikumud
  MUSH, MUD, MUCK, MOO — what the words mean — /reference/mush-mud-muck-moo