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