Player's Secrets of Halskapa is a supplement for the Birthright campaign setting, which focuses on Halskapa, the most powerful of the Rjurik realms. Halskapa was once united under the rule of King Bervinig, but is now on the verge of civil war. Halskapa is the focus of the ambition of many regents, and the security of its magical sources and the trade center have become neglected with all the political infighting. This struggle between prominent jarls for the throne encompasses the majority of the supplement, and information on the realm is contained in short topographical paragraphs and possible scenarios.
David Comford reviewed Player's Secrets of Halskapa for Arcane magazine, rating it a 6 out of 10 overall. He comments that "Halskapa is a personification of the growing internal conflict and turmoil facing the Rjurik people." Disappointed by the focus of the book, he states: "Heralded as the most important of the Rjurik realms, this domain needs more than a mere booklet focusing on the political strife to the detriment of all else." Comford concludes his review by saying, "If you are planning to run a struggle-for-power campaign, then this supplement contains vital information on the major NPCs and a couple of well-presented maps. As a supplement forcus on the Halskapa realm, however, it's merely a useful series of notes and maps."