I personally have always thought that AC had no need for a sandbox. The sandbox elements in the first game were a complete waste of time and effort as the game was completely mission-based. Every activities were appearing in a new district opened by a mission, and they disappeared after the mission has been completed. You could easily remove the sandbox from the game, and it would just become better. If anything, I think that AC should've been Hitman: Blood Money in Middle Ages. I mean: series of missions done in big open levels with many ways to assassinate your target. Preferably by using stealth and/or parkour, not zerg rash.