Cascading impact of lag on Quality of Experience in cooperative multiplayer games

Playing online games should be fun. One of the primary causes of player frustration in online games is lag, or delay in exchange of game state data [1]-[8]. Current lag mitigation strategies are based on the assumption that a player's Quality of Experience (QoE) is influenced only by her own lag [9]-[12]. We systematically show that this assumption is incorrect, because in an online cooperative game the change in QoE of one player due to their lag can have a cascading effect on the QoE of the other players. Our results are obtained through a novel experimental framework based on previous QoE and online game research. Understanding a player's QoE as a cascade function that includes other players' network conditions provides valuable information for designing cooperative online games. Based on our observations, we recommend changes to the current approach to lag mitigation in cooperative games. We argue that the primary objective of lag mitigation should not be to reduce the lag of all players. Instead the primary objective should be to reduce the lag of the most lagged player within each cooperative group.