Cheat mode:
Hold L1 + L2 + R1 + R2 and rotate the Left Analog-stick until "Devil May Cry" is 
spoken at the starting menu. This will unlock all bonus modes, alternate costumes, 
and gallery entries. 

Alternate costumes:
Successfully complete the game under the easy or higher difficulty setting to 
unlock shirtless Dante, under the normal or higher difficulty setting to unlock the 
original Devil May Cry Dante, and under the hard difficulty setting to unlock the 
shirtless original Devil May Cry Dante. Press L1 or R1 at the mission selection 
screen to choose the new costume.

Gallery:
Successfully complete the game under the easy or higher difficulty setting. Note: 
Higher difficulty settings will unlock additional selections.

Hard difficulty:
Successfully complete the game under the normal difficulty setting. 

Dante Must Die mode:
Successfully complete the game under the hard difficulty setting. 

Heaven or Hell mode:
Successfully complete Dante Must Die mode.

Play as Legendary Dark Knight/Sparda:
Successfully complete the game under the hard difficulty setting. 

Unlimited Devil Trigger:
Successfully complete Dante Must Die mode.

Control loading screen:
Press Triangle to slash or Square to shoot at the "Now Loading" screen.

Alternate ending sequence:
Kill at least 100 opponents during the credits. 

Infinite Devil Trigger:
Beat Dante must die mode to unlock the Devil Trigger. 

Clip Reloading:
Tap L2 after firing a slow to reload weapon (i.e., shotgun) and flick it back to fire it 
again. It is slightly faster than waiting for the weapon to reload. 

Mission 3: Shotgun:
Can be found hanging on the wall of the front bar. 

Mission 6: Artemis:
Insert the last item into the statue in the Mute Goddess statue to get this weapon. 

Mission 9: Spiral:
This weapon can be found on the platform in the subterranean lake. 

Mission 16: Kalina Ann:
Defeat the Lady to get this weapon. 

The Trial Of Intelligence:
In mission 5, the trial of intelligence involves a hazy and misleading clue. Take a 
look at the skulls above each doorway and note how many "red dots" there are. 
Each door will thus have one, two, three, or four red dots. Enter doors 4, 2, and 3 
to claim the essence of intelligence. How this relates to the riddle printed on the 
trial's pedastel is a question best answered by Capcom's translation department. 

The riddle in Mission six for Trial of Intelligence is the classic "Riddle of the Sphinx" 
from greek mythology. The Door with four dots represents a baby's hands and 
feet as crawls on the ground. The door with two dots represents the two feet of a 
young man standing upright. The door with three dots represents the old man 
walking on a cane. Go in the doors in that order as instructed in the riddle. 
Knowing this reasoning will better help a player remembering the order 4, 2, 3. 

Pick A Boss:
In mission 18, you need to fight several bosses all over again. The different 
coloured lights on each "Mega Man" boss platform corresponds to: 

Orange - various demons 
Light Blue - Cerberus 
Gold - Gigapede 
Green - Agni and Rudra 
Red - Leviathan 
Purple - Nevan 
White - Beowulf 
Blue - Geyron 
Black - Doppelganger 

Orb Mania:
A great place for orbs is the fifth secret mission found on stage 9. Go through the 
level untill you get to the area where you get the spiral. Go through the 
passageway underneath the waterfall and up through a small tunnel directly across 
from where you. The secret mission is marked by a few bright glowing crystals. 
Once inside you must destroy every breakable object within 40 seconds. The 
jukebox contains 500 red orbs, although there are many other things to smash as 
well. Since you can repeatedly pass/fail this mission and not encounter any 
enemies, you can repeat this process for lots of easy orbs!

Mission 3: Cerberus Devil Arms move: 
Successfully complete Mission 3 by defeating Cerberus to get the Cerberus Devil 
Arms move.

Mission 3: Shotgun:
Can be found hanging on the wall of the front bar. 

Dante swings on stripper pole:
In the strip club, press X then Triangle near the pole to watch Dante swing around.

Mission 5: Agni and Rudra Devil Arms move:
Successfully complete Mission 5 by defeating Agni and Rudra to get the Agni and 
Rudra Devil Arms move.

Mission 5: Breath Of Fire reference:
At the end of Mission 5, after defeating the two brothers, they will tell you their 
names. Agni and Rudra are the names of the last two dragon transformations you 
receive in Breath Of Fire for your hero.

Mission 6: Artemis:
Insert the last item into the statue in the Mute Goddess statue to get this weapon. 

Mission 9: Nevan Devil Arms move: 
Successfully complete Mission 9 by defeating Nevan to get the Nevan Devil Arms 
move.

Mission 9: Spiral:
This weapon can be found on the platform in the subterranean lake. 

Mission 12: Quicksilver style:
Defeat Greyon at the end of Mission 12

Mission 14: Beowulf Devil Arms move: 
After completing Mission 11 by defeating Beowulf, collect the weapon at the start 
of Mission 14.

Mission 16: Kalina Ann:
Defeat the Lady to get this weapon. 

Mission 17: Doppleganger style:
Defeat Shadow Enemy at the end of Mission 17

Mission 19: Yamato Devil Arms move: 
Play as Vergil in Mission 19 to use the Yamato Devil Arms move. It is only usable 
in the Boss fight in this mission after Dante is taken by the Boss.

Glide while in demon form:
You can glide while in demon form by having the Rebellion equipped. Hold R1 + X 
to glide. This move will not appear in the library, but is automatically learned. 
Alternately, you can purchase the Air Raid maneuver for the Nevan weapon.

Fire the shotgun faster:
when using Ebony & Ivory and the shotgun, you can shoot the shotgun faster by 
firing, switching to Ebony & Ivory with L2 (default), firing once or twice with them, 
then switching back to the shotgun. If timed correctly, you can fire the shotgun as 
if it were one of your pistols. Note: This trick can be used with other weapons, 
such as Artemis, but may not work as well.