Perform the following actions to unlock cheats which you can toggle on
in the Options menu. Note: You can only use cheats while replaying memories.

Beat Sequence 1 with 100% Synch - Ride the Unicorn / Turn all horses into 
                                  Unicorns, weapons are electric.
Beat Sequence 2 with 100% Synch - Buns of Steal / Invincibility.
Beat Sequence 3 with 100% Synch - Killing Spree / Assassinations cannot be 
                                  blocked.
Beat Sequence 4 with 100% Synch - Sisterhood / Assassin's Guild recruits are 
                                  all female.
Beat Sequence 5 with 100% Synch - Ultimate Guild / Assassin's Guild recruits 
                                  are Assassino rank.
Beat Sequence 6 with 100% Synch - Calling all Assassins / No cooldown timer 
                                  when calling Assassins.
Beat Sequence 8 with 100% Synch - Desmond Everywhere / Desmond skin.