One of the breakout hits of 2015 was Ubisoft's Rainbow Six: Siege. It was released during the tail end of the holiday shopping season, didn't get a lot of air time and seemed like a throwaway, yet it wasn't! Despite the game becoming a huge success for Ubisoft, the developers have explained why it won't be getting any new game modes.
Remy revealed the news during a preview event in Montreal, Canada. It was explained that the core of the game centers around destructible environments, saving hostages and the back and forth competitive elements of two teams.
While it's possible that the developers could implement a new game mode for Rainbow Six: Siege of some sort; but they would have to do so outside of the black box offered by Siege Mode. This would effectively put them back at square one in trying to figure out how to tie the current structure of the game into a new game mode.
I'm sure a lot of fans are clamoring for a full-on single-player mode, similar to the older Rainbow Six titles where you selected your squad, mapped out their actions, selected their equipment and tactically stormed environments using smarts, precision, and indomitable force. The major problem is that the older Rainbow Six games had levels that weren't designed like arenas. They featured multiple stories, multiple hostages, and lots of enemies.
Part of Rainbow Six: Siege's core design resides in its destructible environments. Completely changing the level layouts where that feature is limited or no longer viable means you also have to change how operator skills are utilized. Changing the skills would also require changing the way the AI behaves and interacts in stages. That's not to mention that for PvP modes the levels would have to be designed in some way to accommodate a balanced take on the versus modes.
It's not that it can't be done, but as Marquis points out, it's something that they simply don't want to do. Rainbow Six: Siege is a unique game and creating traditional multiplayer modes would just made the title feel like every other multiplayer shooter out there. This means that gamers will continue to get new maps, new operators, new weapons and new gadgets, but new modes won't be arriving for the game.
I suppose it's a fine tradeoff so long as the sequel actually contains a full featured single-player mode and still manages to keep the fully destructible environments.