Green Ronin released Cthulhu Mythos, a rules sourcebook and campaign setting for Fantasy AGE 2nd Edition. Though designed for 2e, the book is cross-compatible with previous editions of the AGE system as well as other settings such as Modern AGE. From the product description:
Beyond Fantasy and Horror Lies the Mythos
From the start, the Cthulhu Mythos has been a prime inspiration for fantasy games. Now Fantasy AGE Cthulhu Mythos expands that influence for Fantasy AGE players, giving them everything they need to run a Mythos-corrupted campaign, from new character options and forms of magic, to dark grimoires, new monsters, and straightforward guidance for using the Cthulhu Mythos in fantasy games.
Cautiously gaze upon what lurks within:
Fantasy AGE Cthulhu Mythos requires the second edition Fantasy AGE Core Rulebook to fully use its contents, but like all Adventure Game Engine (AGE) RPGs, can be adapted to other AGE System games with minimal effort.
- New Deepblooded and Dreamghoul ancestries, to start play with the Mythos in your blood.
- New talents and specializations, from the mighty Unconquered to the potent, if foolhardy Eldritch Sorcerer.
- Alienation and Fear rules to assault the psyche, and the Dreamlands to explore its strangest notions.
- Eldritch sorcery, from strange arcana to a detailed ritual magic system.
- Detailed GM advice, including new rules to turn monsters into Mythos horrors, and a selection of fantasy creatures inspired by the Cthulhu Mythos.
- Notes for incorporating elements from Fantasy AGE’s sibling, the modern horror Cthulhu Awakens roleplaying game.
The 64-page digital book is available in PDF now from Green Ronin’s webstore and on DriveThruRPG for $9.99.