Source port cheat codes

Doom 95
The prefix "fh" stands for the initials of Fred Hommel, the Doom 95 author who created the codes.

The "hall" in "fhhall" refers to Jason Hall, CEO of Monolith, who requested that particular cheat (hence the "BY REQUEST..." message that displays when the code is executed).

Eternity
As well as supporting the additional Boom/MBF cheats, Eternity adds a number of its own.

ZDoom
In order to use cheat codes in ZDoom, the variable "sv_cheats" must be set to "1" (true). This variable can be set by launching ZDoom, accessing the console via the tilde ( ~ ) key, and typing "sv_cheats 1". One should then be able to use any ZDoom-specific cheat by typing it into the console.