AC: Unity and Rogue will release on different platforms, Unity on current-gen and Rogue on last-gen. With every gen come a lot of improvements to the technology supporting the games in almost every way, including graphics, AI, scope of the world, scale of the world, many of which can change the way we play games, and vastly increase how much we are immersed in the game.
AC: Unity is good example of this as it is bringing many new things to the series, something not possible in AC: Rogue:
1. Massive number of NPC's on-screen: This can have huge effect on how the game is played. It is good for the stealth-minded but bad for those who like to take enemies head-on, and then quickly escape. This can also make the world feel more alive, which is important in an open-world game.
2. Many more interiors: This vastly increases the immersion of the game, and can lead to new ways of fighting enemies, or escaping from them.
This list will likely expand, as I'll be able to point out many more of these improvements once I play the game.
