It is a time of war. Many leaders from different factions fight to control their land. One such leader, Liu Bei, has only one wish: peace. But war stands in his way, after his land Shu is attacked by the kingdom of Wei, led by the warlord Cao Cao, who abducts Liu Bei's beloved Diao Chan, the keeper of the Imperial Seal. Liu Bei has to flee, but swears to return, exact revenge on Cao Cao, and liberate the kingdom of Shu.

Kessen II is a real-time strategy game, and a follow-up to Kessen. Unlike the first game, it is set in the Chinese Three Kingdoms period. The account of historical events is heavily fictionalized in the game, liberally adding new sub-plots (such as the entire romance angle of the story) and supernatural elements. The player can choose to command the armies of either Liu Bei or Cao Cao in their respective scenarios.

The gameplay is similar to that of the previous game, the most notable change being the shift to supernatural warfare, including the addition of magical attacks such as tornadoes, lightning strikes, earthquakes, meteor showers, etc. The player can now control 500 units at one time, as opposed to 100 in the previous game. New unit types (elite horsemen, elephant cavalry, etc.) have been added.