Game mode in Perfect Dark where you can play solo missions co-operatively. The 1rst player (Joanna Dark) gets supported by either a human player in the role of Velvet Dark (Jo's sister), or an AI-controlled "buddy". There are several cheats in the game to be unlocked, making it possible to get AI support from a different characters such as a Maian or Mr. Blonde.
There is a league called the Perfect Dark Co-operative World Rankings , where several Perfect Dark gamers are ranked as teams with their best personal records. Though this mode has never been played intensively (because players don't get to meet often), on several stages Co-operation times get below the Single Player world records. This is possible because two players can split up on stages and devide objectives, which makes room for new strats resulting into many timesavers.
The Co-operation mode has been critized a lot by its framerate problems. In many cases the framerate drops significantly when multiple characters have to be rendered by the N64 system. This is not only a problem for players to speedrun, but it also makes the game way harder to complete.