It allowed one player to serve as a Dungeon Master, shaping and altering the game world against a party of human-controlled players, playing cooperatively. (An earlier game, Vampire: The Masquerade – Redemption (2000) was the earliest CRPG to feature this sort of "storyteller" mode.) Contemporary MMORPGs such as Blizzard Entertainment's World of Warcraft feature a mixture of single-player goals ("quests") and larger end-game challenges that can only be completed via intensive co-op play, of up to twenty-five (formerly forty) players in end-game raids, and up to forty versus forty in battlegrounds. Gameplay characteristics Couch co-op and online co-op modes Cooperative games designed to be played by multiple players on the same display screen have come to be known as "couch co-op", "local co-op" or "single-player co-op" games. Cooperative games in which players each use their own display system are known as "online co-op", "network co-op" or "multiplayer co-op" games due to the majority of such systems utilizing telecommunications networks to synchronize game state among the players. Games have also been brought to market in which both modes can be combined—accommodating more than one display with each display accommodating one or more players. While there are no practical technical limits to how many players can be involved in a cooperative game, the industry has settled on games that support up to four players as a informal standard. This comes from a combination of factors. Historically, cooperative arcade video games maxed out at four players. Similarly, consoles which supported local co-op play on the same screen also maxed out at four players. There is also a human factor according to various developers. While having more than four players involved could make a game more interesting to play, this starts to exceed a comfortable number related to social interactions between players and may cause segmenting of the larger group into smaller ones, while up to four players encourages cooperation and coordination within that group. Display features Many video games support split screen displays in order to show two or more players in different regions of the game. Split screen displays would usually split the main screen into either two or four sub-regions so that 2–4 players can roam freely within the game world. Many first-person and third-person shooter games use this technique when played in multiplayer co-op mode, such as the console versions of games in the Rainbow Six series, the Halo series