
For their letters, players first make up a character, or choose one of Lovecraft's, and play in either the 1920s or the present day.

This is the section that focuses on the writing of letters. The first section, Letters from the Abyss, makes up the largest portion of the book. And thus, it is also itself a work of fictionan enjoyable pastiche of the Lovecraftian milieu. Not only is it a set of rules and instructions explaining how to play, it is also an example of how to playthe rules are laid down as a series of letters from Michal to one of his friends, becoming more and more erratic as he approaches the end of the book. That text contains a tale that actually works on several different levels. De Profundis somehow manages to combine all three of those elements into the very same text.

Most roleplaying games contain rules, play examples, and game-world fiction. It seems very similar to the freestyle form of roleplay used in MUSHes and other on-line roleplay environments.

Psychodrama, as explained by an article in an appendix, is a diceless, game-masterless method of roleplaying, in which the course of the narrative is decided by the course of conversation among the gamers. De Profundis, an English translation of a roleplaying game from Poland, is a 32-page booklet containing a set of rules for epistolary psychodramaa sort of roleplaying by letterin the world of Lovecraft's Cthulhu mythos.
