The Hidden Blade Assassin's Creed in Depth

The goal in this video is to kill the targets of Sequence 13 as quickly as possible, while remaining Anonymous, if possible, up through the start of the kill animation. The missions in this video are loosely ordered from easiest to hardest to design.

Surgical Strike
It's tempting to try long-distance throwing knives (see Arch Nemesis), but you'll find that they fall a few inches below the target's feet. Oh well.. just run around the guard post for a quick, easy kill.

Doomsday
There are fewer guards wandering around the streets after reloading the mission, which makes it much easier to kill the target quickly.

Still Life
After jumping down from the roof, throw down a smoke bomb as you start to move. This keeps you from becoming Exposed as you run up the first set of stairs.

Upward Mobility
This blitz design only works on the initial attempt after accepting the mission. As the screen fades from white, you'll need to position Ezio while "blind" so that he stands next to the crates. Once you have a clear view, run up the crates and intercept the target as shown. If you fail your attempt, abort the memory so that you can try again.

Arch Nemesis
When you are not locked on, throwing knives will travel in the direction of your last horizontal movement. Hop down and horizontally aim your throwing knives by looking over Ezio's head as he walks. The vertical aim is controlled by Ezio's elevation, which can be adjusted by positioning Ezio along the slope of the roof. You'll likely need to unleash several throwing knives to score the kill.

Climbing the Ranks
Start off by double tapping the Legs button to force a jump through the group of Agiles, knocking them out of your way. Start climbing, and hope nothing hits you in the butt. When you reach the top of the scaffold, go up the first ladder, but do not use the second ladder. Instead, run up the wall and pull yourself up to the top. Avoiding the second ladder slightly delays the guards on the top roof from entering the barricade formation, allowing you to run past them.

It might be possible to use throwing knives (or pistol) on the target when you reach the top of the scaffold, but I haven't been able to do this successfully.

Port Authority
This mission was started after a reload. The initial attempt on this mission places Ezio in a different starting position than what is shown here... so be careful on the initial jump off the roof on your first try. If you like, you can stay hidden from the archer on the dock a little longer by swimming underwater after you round the corner while swimming.

Hitting the Hay
Despite the appearance of a straightforward blitz, I find this mission to be among the most difficult to execute. The aim on the first leap has to be perfect in order to free-run seamlessly onto the next building. It's tempting to try an air-assassination from the fence, but Ezio doesn't have the range to pull it off.

Last Rites
This particular wall of the Duomo allows you to climb up very quickly. Jump in the haystack and pop out. (Now scratch your head and wonder why hay would be needed on the roof of the Duomo. Perhaps to feed the flying horses?) Run up the side of the half-dome, and jump left. Pull yourself up a little and jump right to get on top of the half-dome. Continue up to the top of the tower. The quickest way to kill the target is to use a single throwing knife. Ezio becomes Unseen (yellow ring around the mini-map) just before the knife hits the target. It's debatable whether this counts as an Anonymous kill. It's trivial, of course, to adapt this mission design to make it completely Anonymous, but doing so would make it a few seconds slower.