Rainbow Six: Siege was the surprise end reveal for Ubisoft's E3 conference this year, with the shooter sequel replacing the original in-development Patriots title in name, look... just about everything.
The drastic change for the latest in Ubisoft's tactical shooter series, explained technical artist Oliver Couture to RPS, was due to the studio's attempts at new gameplay mechanics (destructible environments) that proved too much for the older gen systems too handle, and so the team decided to start again on new-gen only.
"Next-gen consoles were just around the corner," he explained to the site, "and we were like, ‘OK, we want to also have a next-gen experience. What can we do for that?' We were trying stuff out with destruction technology, and we realized destruction really changes the game. We tried to see how it could fit with old-gen, but it just didn't work out. So for us it was just a better solution to clean the slate, reset, and make what's best for the players".