A roleplaying game is an event where players take on agreed-upon roles within an agreed-upon premise to accomplish an agreed-upon objective. Those roles make it roleplaying (somewhat tautological, I know), and both the objective and the premise make it a game. That objective and that premise are defined in combination by the players of the game and the ruleset they have chosen, and that objective and that premise are more foundational to assessing a roleplaying game than either the players or the ruleset.