Castles: The Northern Campaign is an expansion and an improved version of Castles, the strategy game developed by Quicksilver and published by Interplay. The original game and the expansion were released in 1991 for DOS, while the Amiga version was released in 1992.
Designed by Scott Bennie, Bill Fisher, and Bryon Garrabrant, Castles was a realistic medieval "city-building" sim involving construction, management, combat, finance, and more.
The Northern Campaign improves the game even more. Reviews were very positive, and many consider this one the best chapter of the Castles series.