Heir to the Throne (HT3) is a 2-4 player card game of treachery and sabotage where players compete to build noble families and fight each other for the throne of King Graham, the aged ruler of Wysteria. Each player is responsible for building their lineage and defending their family members from rival families.
This is done through a family tree style playing field. Players begin the game with a Noble House Card that shows both a Lord and Lady. From there, players use Court Drama Cards to arrange marriages and have children and thereby grow their family tree. Each character can play two Court Drama Cards on their turn to maintain and develop their own family tree, or attack their rivals.
In addition to helping characters wed and have children, some Court Drama Cards also let players make others illegitimate or infertile, preventing them from winning the throne. Likewise, other Court Drama Cards allow players to remove these negative effects and to restore themselves to their former glory.
In order to win the throne, a noble family must produce at least one great-grandson that is of age and neither illegitimate nor infertile.