Tom Clancy's Rainbow Six is a 1998 tactical shooter video game developed and published by Red Storm Entertainment for Microsoft Windows, with later ports for the Nintendo 64, PlayStation, Mac OS, Game Boy Color, and Dreamcast. It is the first installment in the Rainbow Six series. Based on the Tom Clancy novel of the same name, the game follows Rainbow, a secret international counterterrorist organization, and the conspiracy they unravel as they handle a seemingly random spike in terrorism. In singleplayer, the player advances through a series of missions in a campaign. Before each mission, the player is briefed on the situation, selects and organizes their operatives and equipment, and plans their movement through the level; during missions, the player controls an operative leading computer-controlled teammates as they follow the player's plan. In multiplayer, players cooperate in player versus environment missions or battle to complete objectives in player versus player matches. The game features realistic gameplay factors, weapon lethality, and consequences for failure, forcing players to plan their approach carefully and promoting replayability for more streamlined completion. Rainbow Six began as a concept by Red Storm following their formation in 1996. The game was developed in parallel with the Rainbow Six novel, with a design philosophy of realism and strategy guiding all aspects of development; however, numerous setbacks stymied the game's development and forced the developers to crunch. Though his name is in the game's title, Tom Clancy's involvement in Rainbow Six's development was very minimal. Red Storm developed the PC version, while all other ports were developed by their respective companies. Rainbow Six was released on August 21, 1998 to widespread critical acclaim, though the console ports received relatively lower ratings than the PC version. For most releases, praise was directed toward gameplay, multiplayer, immersion, and the game's combination of strategy and action, while criticism mainly centered on AI issues, glitches, and the graphics and controls of some ports. The game sold over 200,000 copies in its first year of release and continued to sell hundreds of thousands more copies well into the early 2000s. Rainbow Six was nominated for numerous accolades and has been deemed one of the best video games of 1998. It is considered a milestone in the history of first-person shooters and made a lasting impact on the then-fledgling tactical shooter genre. An expansion pack, Tom Clancy's Rainbow Six Mission Pack: Eagle Watch, was released on January 31, 1999. A sequel, Tom Clancy's Rainbow Six: Rogue Spear, was released in 1999. A loose mobile game remake, Tom Clancy's Rainbow Six: Shadow Vanguard, was released in 2011.