was more successful in its NES incarnation than it was in the arcades in the North American market, and is now considered one of the most popular co-op games ever. Gunstar Heroes for the Sega Genesis and the Metal Slug series for the Neo Geo were also well-received titles. Electronic Arts has produced key co-op sports games, including the original NHL Hockey (1991) and Madden NFL (1990) installments on the Sega Genesis. These games allowed two players or more to play against the CPU. These franchises are arguably the most successful co-op sports games. Due to the lack of online multiplayer, co-op games in the RPG genre have generally been less common on console systems than on PCs. Nevertheless, some of the earliest co-op action RPGs were console titles, including the TurboGrafx-16 game Dungeon Explorer (1989) by Atlus which allowed up to five players to play simultaneously, and Square's Secret of Mana (1993) for the Super NES which offered two- and three-player action once the main character had acquired his party members. Secret of Mana's co-op gameplay was considered innovative in its time, as it allowed the second or third players to drop in and out of the game at any time rather than players having to join the game at the same time, which has remained influential on titles as recent as the upcoming Dungeon Siege III. Final Fantasy VI (1994) offered a form of alternating co-op play for its battles, with the second player taking control of half of the characters in the party. Namco's Tales series allowed multiple players to take control of individual members in its real-time battles in some of the titles, such as Tales of Symphonia, while the Baldur's Gate: Dark Alliance games replicated the Diablo formula for consoles, offering two-player simultaneous play through the game's campaign. With the release of the Nintendo 64 (1996, 1997), having four controller ports started to become a standard feature in consoles, as the Dreamcast, Nintendo GameCube and Xbox all later featured them. As larger multiplayer games became feasible, cooperative gameplay also became more available. The 7th and current generations of video game consoles all feature wireless controllers, removing port-based local player limits. However, its effect on multiplayer is probably less pronounced than the advancement of console internet capabilities. PC co-op gaming First-person shooters The release of Doom in 1993 was a breakthrough in network gaming. Though arguably