1. A server device comprising: a game management unit that manages progress of a network game in which a plurality of users are allowed to simultaneously participate through communication lines across a plurality of terminals; a ranking processing unit that calculates a contribution degree to the network game as an active level for each participating user during progress of the network game managed by the game management unit and determines a ranking; and a display configured to display a participating user from the plurality of users in accordance with the ranking determined by the ranking processing unit; wherein the game management unit comprises: a receiving unit that, in a team formed by users having collaborative relationships with each other among users participating in the network game, receives an instruction action for the same objective from a user belonging to the team for a predetermined limited time; and an excitement level processing unit that calculates an excitement level based on a total amount of the instruction actions from each user within the same team, the instruction actions having been received by the receiving unit through the plurality of terminals, and the game management unit allows the network game to progress in accordance with the excitement level calculated by the excitement level processing unit.