From the publishers blurb:
Depending on who you ask, Gemeria was a hero, sorceress, illusionist, artificer, witch, artist, poet, trickster, seductress, or villain. She made her mark on history, becoming incorporated into children’s fables playing all of those roles. Her cryptic language of mystic glyphs is carved into the walls of every significant city and dungeon in the world. A century later, her secret lair has been discovered, potentially holding the key to her secrets. The race is on to decipher her code and profit off the knowledge and power contained in her home.
The Gemeria Code is an Old School Tabletop RPG Adventure for 3rd to 5th Level Characters - Compatible with Old School Essentials. Free Preview found on my Itch page. See the review on Age of Dusk!