The German Lovecraftians report, of their open-source ‘original Lovecraft’ FHTAGN role-playing game, that…

Dean Engelhardt […] has now translated the FHTAGN game world into English, made his own minor adjustments and published it as The Open Cthulhu Mythos SRD (System Reference Document) (2023).

This is now a pay-what-you-want Open Game License book on the DriveThruRPG store.

There is however still scope for a book designer / illustrator to swoop in and help out…

This PDF contains the text of a full set of game statistics describing the creatures, rituals, and artefacts from Lovecraft’s original Cthulhu Mythos. In OGL terms it is a “System Reference Document” (or SRD). [It is not yet] presented in a fully illustrated and typeset form as you would expect from a core RPG rulebook.

Which means…

[It is not an] all-in-one Cthulhu Mythos RPG corebook (which traditionally cover both rules and “world” in the one volume)

As it stand it may thus interest purist Mythos writers as well as gamers, being only about Lovecraft’s creations and with only a core of RPG mechanics currently added.