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.
Dual Wield and Mini-Gun:
Dual Wield is unlocked by completing Directors' Cut and the Mini-Gun by completing Story Mode.
Complete Story Mode to unlock the longer Director's Cut stages, which have alternative paths that let you unlock the rest of the collectibles.
Papa's Palace of Pain - Complete 'Papa's Palace of Pain' in Story Mode.
Naked Terror - Complete 'Naked Terror' in Story Mode.
Ballistic Trauma - Complete 'Ballistic Trauma' in Story Mode.
Carny - Complete 'Carny' in Story Mode.
Creeping Flesh - Complete 'Creeping Flesh' in Story Mode.
Scream Train - Complete 'Scream Train' in Story Mode.
The Fetid Waters - Complete 'The Fetid Waters' in Story Mode.
Jailhouse Judgment - Complete 'Jailhouse Judgment' in Story Mode.
Overkill - Complete all levels in Story Mode.
Goregasm! - Achieve a Goregasm.
Weak At The Knees - Maintain a Goregasm for 2 minutes.
De-Generation - Collect 10 LPs.
Decom-Poster Child - Collect 15 posters.
Dis-Figurine Collection - Collect 15 figurines.
Graphic Horror - Collect 17 comic book pages.
Boom Headshot! - Decapitate 200 mutants.
Toasty! - Kill 5 or more mutants with one grenade.
Yakuza - Kill 100 mutants 'Gangster Style' (holding gun sideways).
Suffer Like G Did - Complete any level with only one health segment remaining.
Hardcore - Complete any level in Director's Cut without using any continues.
Merchant of Menace - Buy a new weapon.
Fully Loaded - Fully upgrade any weapon.
Power of the Mind - Complete any level with the targeting crosshair off.
I'll Try Anything Once - Play each minigame through to completion once.
Lights, Camera, Headshot! - Complete all levels in Director's Cut.
Caesar's Salad - Complete all CHALLENGES for 'Papa's Palace of Pain'.
Private Dance - Complete all CHALLENGES for 'Naked Terror'.
Doctors and Nurses - Complete all CHALLENGES for 'Ballistic Trauma'.
Clown Shoes - Complete all CHALLENGES for 'Carny'.
Meat Packer - Complete all CHALLENGES for 'Creeping Flesh'.
Bad Conductor - Complete all CHALLENGES for 'Scream Train'.
Swamp Monster - Complete all CHALLENGES for 'The Fetid Waters'.
Jail Bird - Complete all CHALLENGES for 'Jailhouse Judgment'.
Lab Rat - Complete all CHALLENGES for 'Overkill'.
Never Runs Dry - Complete a level without triggering an enforced reload (i.e. reaching zero bullets).
Be My Valentine, Jill - Unlock all unlockables and purchase all weapons.
Perfect Victory - Achieve an S rank for all levels in Story Mode or Director's Cut.
Do You Feel Lucky? - Complete all levels in Classic Mode without using any continues.
Extreme Hardcore - Complete all Director's Cut levels in Hardcore Mode.
The House of the Dead: Overlord - Earn all Bronze, Silver, and Gold trophies.