Mount and Musket Battalion is a multi-player total conversion that tries to accurately represent the time period around the end of the Napoleonic Wars (1812-1815). It has historical factions with accurate units and equipment, including different types of infantry, cavalry and even usable artillery.
Good strong multiplayer community, slighty uptight but they have to enforce these rules to keep the game from dropping from fun to unfun.
Give it a go with friends.