Unlock Crisis Missions:
Clear the Rescue Mission to unlock the Crisis Missions.
Unlock Infinite Ammo:
Beat the game at normal difficulty to unlock unlimited ammo for the grenade launcher, uzi, and shotgun.
Unlock Infinite Credits (Alternate):
By simply dying in arcade mode, your continue credits increase by one each time. This will go into infinite credits after more than six failures.
Unlock Infinite Credits (Arcade Mode):
Clear Story mode on Arcade settings. Credits are now set to Freeplay (and life points may also be increased to nine).
Unlock Infinite Handgun Magazine:
Clear story mode on arcade settings using only the handgun (do not pick up any other weapon!).
Unlock Infinite Special Weapon Magazine:
Clear story mode on arcade settings under 30 minutes (00:30:00.00).
Unlock Mirror Mode:
Play through the story mode on arcade or rescue settings without continuing to unlock Mirror Mode in Arcade Mode or Rescue Mode.
Unlock New Title Screen:
Clear the Rescue Missions for a new title screen.
Unlock Rescue Missions:
Clear the game once to unlock the rescue missions.
Unlock Trial Mode:
Clear any stage in arcade mode to unlock its trial mode.
Source? Here it is.
Clear the Rescue Mission to unlock the Crisis Missions.
Unlock Infinite Ammo:
Beat the game at normal difficulty to unlock unlimited ammo for the grenade launcher, uzi, and shotgun.
Unlock Infinite Credits (Alternate):
By simply dying in arcade mode, your continue credits increase by one each time. This will go into infinite credits after more than six failures.
Unlock Infinite Credits (Arcade Mode):
Clear Story mode on Arcade settings. Credits are now set to Freeplay (and life points may also be increased to nine).
Unlock Infinite Handgun Magazine:
Clear story mode on arcade settings using only the handgun (do not pick up any other weapon!).
Unlock Infinite Special Weapon Magazine:
Clear story mode on arcade settings under 30 minutes (00:30:00.00).
Unlock Mirror Mode:
Play through the story mode on arcade or rescue settings without continuing to unlock Mirror Mode in Arcade Mode or Rescue Mode.
Unlock New Title Screen:
Clear the Rescue Missions for a new title screen.
Unlock Rescue Missions:
Clear the game once to unlock the rescue missions.
Unlock Trial Mode:
Clear any stage in arcade mode to unlock its trial mode.
Source? Here it is.