Reach boss zone 1 without killing any monster or being damaged by them. Game can't be saved.
Beat the game without using secondary weapons
Beat the game without dying or being assisted by doctors. Game can't be saved.
Boss extra 3
Destroy boss zone 3 with a mine
Change a friend's character while he/she is playing
Kill boss zone 3 receiving no damage from it
Pick up any item in less than 16 seconds
Kill boss zone 2 receiving no damage from it
Boss extra 1
Destroy boss zone 1 with a rocket
Kill boss zone 1 receiving no damage from it
Beat the game without dying.
Boss extra 2
Destroy boss zone 2 with a laser