In addition to the run-of-the-mill parkour jumps and wall traversals his predecessors are known for, Assassin's Creed Unity protagonist has a new trick up his sleeve: crouching.
Up until now, stealth in Assassin's Creed games have been contextual where players are allowed to hide in haystacks or among a group of monks, but not to crouch behind fixtures. Apparently, this behavior was so entrenched in the engine's core, the development team had to rewrite huge portions to enable player-controlled crouching.
"The engine was ... I mean, we rewrote like 6 million lines of code for this," said Alex Amancio, Ubisoft studios creative director. "It's not a joke."
"Our navigation seems very simple and very accessible, but to do this, it means that the system is calculating, before you're actually moving, where the possibilities of where you're actually going to go," he added. "And this is why a lot of people, from previous games, they felt like, 'I didn't want to go there and got detected.' We're trying to favor flow. We don't have a vehicle like Grand Theft Auto, a car and then a character – the assassin does both. So we need to favor flow for the traversal of the city, so a lot of times when you're trying to be stealthy the system is trying to favor speed and flow, and this is why this stuff happens. By creating the stealth mode, what we're actually doing is changing the way the navigation is working, because we know that you want to be stealthy."