Across a dozen sprawling levels, Besieger uses an innovative economic management system allowing besiegers to build and populate citadels comprised of 40 different types of building and filled with 20 different types of unit. All this is set in a detailed and realistic universe filled with animals and natural elements, a varied climate and even day and night management.

Besiegers can build flying vehicles to wage war or besiege towns on horseback to conquer factions including Ogres, Werewolves and Centaurs. The reinforced walls of a barricade can be broken using a battering ram and players can conquer enemy buildings and equipment, as well as retreat and accumulate forces behind their own armoured citadel for a counterattack.

Besieger supports an army of up to 16 players per server via LAN or Internet and features gameplay including Deathmatch, Capture the Flag, Cooperation, Hold Artefact and Free for All.