Tom Clancy's Rainbow Six Siege is a first-person shooter video game developed by Ubisoft Montreal and published by Ubisoft. Siege was released in December 2015 for Microsoft Windows, PlayStation 4 and Xbox One. The game puts heavy emphasis on environmental destruction and cooperation between players. Players assume control of an attacker or a defender in different gameplay modes such as hostage rescuing and bomb defusing. The title has no campaign, but features a series of short missions that can be played solo. These missions have a loose narrative, focusing on recruits going through training to prepare them for future encounters with the White Masks, a terrorist group that threatens the safety of the world.