Here is the full list of all 24 Mini Ghost achievements.
Find all Twitch Friends
Beat the game without using secondary weapons
Destroy boss zone 3 with a mine
Beat the game without dying or being assisted by doctors
Beat the game without dying.
Kill boss zone 3 receiving no damage from it
Kill boss zone 1 receiving no damage from it
Destroy boss zone 2 with a laser
Destroy boss zone 1 with a rocket
Beat the game
All items in inventory
Find secret room
Pick up any item in less than 16 seconds
Reach boss zone 1 without killing any monster or being damaged by them
Change a friend's character while he/she is playing
Buy everything available
All hp bar unlocked
Obtain card 4
Obtain card 3
Kill boss zone 2 receiving no damage from it
Find night vision goggles
Obtain card 2
Destroy a boss in less than 40 seconds
Beat the game in less than 45 minutes