Here is the full list of all 42 Midnight Ghost Hunt achievements.
Unlock a single cosmetic
Kill 10 Hunters.
Get 10 headshots as a prop.
Win 10 games as a Ghost
Win 10 games as a Hunter
Kill 10 Ghosts.
As a Ghost, taunt 25 times in one game.
Won first game as a ghost.
Won first game as a hunter.
Win 100 games as a Hunter.
Win 100 games as a Ghost.
Kill 100 Ghosts.
Kill a team of 4 by yourself
Get 100 headshots as a prop.
Get 100 kills as a Lamp.
As a hero prop, kill 10 hunters.
As a hero prop, kill 100 hunters.
Taunt 250 times.
As a ghost, possess 1000 props.
Unlock 25 different cosmetics.
Unlock every cosmetic in the game.
Kill 100 Hunters.
250 Spectral Cannon Kills
250 Project X Kills
250 Flamethrower Kills
250 Reaper Kills
250 Frostbite Kills
250 Ghostsmasher Kills
50 Riot Shield Kills
250 Sledgehammer kills
250 Harpoon Bazooka Kills
250 Grenade Kills
250 C4 Kills
100 Doppelganger Kills
100 Telekinesis Kills
100 Corruption Kills
100 Poltergeist Kills
100 Miasma Kills
100 Shoves
Achieve all loadout specific achievements
250 Salt Shotgun Kills
Get 5 Aces