Shadowbane was notable for emphasizing player-versus-player combat, implementing non-conventional races and specializing in siege warfare (players building cities and trying to raze enemy players' cities) whereas a significant number of MMORPGs released since Ultima Online usually restrict player killing to certain areas of the game or special dedicated PvP servers. The game also featured a seamless world map, and made no use of instancing.
Players were also allowed to own cities and capitals and most of the property and cities in Shadowbane were player owned. In effect, Shadowbane's war status was decided by the players rather than the game company. Whether a guild city went to war with another guild city was entirely up to the leaders. A government system was also implemented in the game. It ensured players were in total control of the Shadowbane world.
Though there were no quests in the game, Shadowbane featured PVP, Nation, and Siege Warfare systems, which offered players a wide range of in-game opportunities.
Source: Wikipedia, "Shadowbane", available under the CC-BY-SA License.