If you've been playing Assassin's Creed for a moment, you already recognize that the 100 hidden feathers that waste the game are only the start of what the game presents compulsive collector-types. The real prizes are the Glyphs, 20 semi-hidden signs left plastered on convinced landmarks, which were hacked into the Animus by the mysterious Subject 16. Once you've establish them – which can be tough allowing for the size of some of the marked buildings – you'll then be tasked with solving a brief series of enigmas before you can crack the ever more horrifying conspiracy story within.