
Beat Assignment Ada to unlock the Chicago Typewriter. It has infinite ammo and can be purchased the Merchant.
To unlock the Handcannon, finish The Mercenaries with a 5 star rating on all stages with all charaters.
To complete Ashley's puzzle with ease, take a look at the layout below:
123Numbering the slots from top to bottom in that manner, hit the following positions in this order: 4, 7, 8, 9, 6, 3, 1, 7, 9. Watch out for the knights!
You must get 3000 or more points in Game D.
Without using a Gameshark (or similar device), you can keep the Special Launcher Ada throws down during the final fight. Simply unlock the P.R.L. weapon unlocked by completing Professional difficulty mode to waste Saddler. When Ada tosses out the Special Launcher, get it, and finish Saddler with the P.R.L. When you begin the game again, you will have Special Launcher (note still one shot).
In order to do this trick you need to first pick Leon's gangster outfit, and then equip the Chicago Typewriter machinegun. Reload the machinegun a few times in a row and Leon will pose.
To unlock the Thompson Submachinegun, clear Leon's story mode (any difficulty) and complete Ada's story mode (Separate Ways). Purchase it from the Roma merchant when playing a new game plus.
Ada can also have the weapon available for her own side-story mission (Assignment Ada) simply simply clearing that particular mode once. Again, speak with the Roma merchant to access it.
Clear Leon's Story on Professional difficulty to unlock the PRL 412 weapon. It has two settings -- stun and kill (just like Star Trek) which you may determine by holding or tapping the fire button. It has infinite ammunition.
Clear the Separate Ways mode to unlock more costumes for Leon and Ashley.
Clear the main game (any difficulty) to unlock:
Leon may sit in the red throne after the laser hallway by inspecting it. Nothing interesting occurs, but it makes for an interesting screenshot.
Each weapon has a special "exclusive power" when all of its stats are custom tuned to the maximum: