Short answers, pulled from the story.
Birthright is a Dungeons and Dragons campaign setting released by TSR in 1995, set on the continent of Cerilia on the world of Aebrynis. It is built around the concept of bloodlines, divine power inherited from gods who died in an ancient cataclysm, and allows players to take on the roles of rulers governing nations rather than simply adventuring through them.
Rich Baker and Colin McComb co-designed Birthright in 1994. It was published by TSR and released in 1995.
Birthright won the Origins Award for Best Roleplaying Supplement of 1995 at the 1996 Origins Awards ceremony.
Bloodlines are divine power absorbed by heroes present at the battle of Mount Deismaar, where the gods sacrificed themselves to destroy the dark god Azrai. Characters who inherit this power, called scions, generate an aura of authority called Regency, measured in regency points, which they use to rule domains.
Awnsheghlien are beings who carry the blood of Azrai, the dark god destroyed at Mount Deismaar. Corrupted by this heritage, their bodies warp over time to reflect their inner corruption. Examples include the Gorgon, described as perhaps the strongest creature in Cerilia, and the Spider, who was once a goblin-king present at Deismaar.
TSR published twenty-five roleplaying products and five novels during Birthright's four-year run, along with a computer game by Sierra On-Line called Birthright: The Gorgon's Alliance. The publishing schedule was not fully completed before the line was cancelled after Wizards of the Coast acquired TSR.