1. Age of Omia: The Demon Heart

The first installment in the Age of Omia chronicles, created in 2007 by author and illustrator Stef Brooke-Harris.
Pay what you want :) (free is fine too!)

"When a sand monster attacks Omia an overwhelming temptation is thrown into the clutches of a young academic, Linius Tiathor. Linius can’t resist and sinister things begin to happen beyond the boy’s control. Demons are awakened. Auchrioch, a sinister demon Lord, threatens their world at every turn plunging Linius and his friend, Sernai, into adventure. Set in the age of Omia, a world in which demons roam the land. This epic tale takes you into the lives of the creatures and how they find their demon heart."