Rainbow Six Siege is the shooter out there with the most depth right now, and a lot of that is due to how interesting and complex every single map in the game is. Though they may not all be perfectly balanced, all of the maps have incredibly intricate detail, and it's almost always the team that knows the map better and takes advantage of that knowledge that earns that "W." There are still new strategies being developed on a lot of the maps in the game, even ones that have been there since launch.