A computer-implemented method for use in operation of an entertainment apparatus for determining a lack of user activity in relation to the entertainment apparatus, the method comprising the steps of: obtaining a time series of samples usable to determine activity of users in relation to a plurality of predetermined user-manipulable objects for controlling the entertainment apparatus, the time series of samples comprising at least two of inertial tracking information, image tracking information and acoustic tracking information regarding the position and/or orientation of individual ones of the predetermined plurality of user-manipulable objects with respect to a corresponding activity of individual ones of a plurality of users, wherein the plurality of predetermined user-manipulable objects comprise a plurality of game controllers associated correspondingly with individual users; generating a weighted average of the at least two of inertial tracking information, image tracking information and acoustic tracking information to generate a time series of refined position and/or orientation information for the individual game controllers in relation to the corresponding activity by the individual users; processing the time series of refined position and orientation information to identify one or more individual users of the plurality of users as being currently inactive so long as the activity of the corresponding individual user does not exceed a threshold; and controlling the operation of the entertainment apparatus when the step of processing the refined position and orientation information determines that the user is currently inactive, wherein the step of processing the refined position and orientation information further comprises determining whether one of the plurality of game controllers has been inactive during a game already in progress; and adding a new user to the game already in progress in response to the determination that one of the plurality of game controllers is currently active after determining, in the step of processing the refined position and orientation information, that it was inactive during the game already in progress. obtaining a time series of samples usable to determine activity of users in relation to a plurality of predetermined user-manipulable objects for controlling the entertainment apparatus, the time series of samples comprising at least two of inertial tracking information, image tracking information and acoustic tracking information regarding the position and/or orientation of individual ones of the predetermined plurality of user-manipulable objects with respect to a corresponding activity of individual ones of a plurality of users, wherein the plurality of predetermined user-manipulable objects comprise a plurality of game controllers associated correspondingly with individual users; generating a weighted average of the at least two of inertial tracking information, image tracking information and acoustic tracking information to generate a time series of refined position and/or orientation information for the individual game controllers in relation to the corresponding activity by the individual users; processing the time series of refined position and orientation information to identify one or more individual users of the plurality of users as being currently inactive so long as the activity of the corresponding individual user does not exceed a threshold; and controlling the operation of the entertainment apparatus when the step of processing the refined position and orientation information determines that the user is currently inactive, wherein the step of processing the refined position and orientation information further comprises determining whether one of the plurality of game controllers has been inactive during a game already in progress; and adding a new user to the game already in progress in response to the determination that one of the plurality of game controllers is currently active after determining, in the step of processing the refined position and orientation information, that it was inactive during the game already in progress.