Rainbow Six Siege will, if Ubisoft Montreal has anything to do with it (and they do, what with them being the developers), take the original Tom Clancy action game series back to its roots. The emphasis is squarely on tactical gameplay, with a swift death always waiting around the corner.
Multiplayer is at the heart of the game, and players take on the role of a counter-terrorist operative tasked with ending (the clue's in the title) terrorist sieges. Or, in the multiplayer mode, they might be one of those pesky terrorists themselves. With tactical play at the heart of the game defenders will need to secure their strongholds using teamwork and strategy. Counter terrorism operatives, meanwhile, can use tactical maps, observation drones and a new rappel system to work out how to deal with their enemies.
As 'short-range' specialists, players will need to work primarily in indoor, close-quarters environments as bullets fly all around them. Right at the core of the game is a previously unseen level of destructability in the environment. When you can breach a floor or ceiling to gain access, or rip holes in walls to create new lines of site, everything about how you play changes. Lots of care has been put into just how the environment changes into smithereens, too, and the effects will change depending on things like the calibre of your bullets and the type of explosives you have used.
Complementing the multiplayer mode is a series of 'Situations'. They don't make up a campaign as such, but they do offer the player a range of missions to tackle solo, so that they can hone their skills away from the furious action of multiplayer.