Three-dimensional virtual space is often regarded as one of the more appealing characteristics of multiplayer online games, but the actual use of that space remains one of their more under-studied features. Consequently, accounts of what people actually do in multiplayer online games are incomplete, as is our understanding of what 3D contributes to the game. To address this lack, a systematic study of game tactics is needed. This paper argues for this need, and describes methods for tactical analysis developed to analyze recorded games from the open-source online game BZFlag.