The crossbow is unlocked by completing all stages in Director's Cut. This weapon fires explosive quills. Like the mini-gun, the weapon is already fully upgraded when bought. Unlike other weapons, the shot from the weapon does not count towards the Combo bonus, only the explosion. Also, the explosion only affects bosses and zombies; it will not "hit" items you need to collect (cash, 3D models, concept art, sound tracks, etc.). To collect such items with the crossbow, your quill must strike the object itself.