Here is the full list of all 28 EMPTY SHELL: DEMO achievements.
Kill 350 Small Spiders
Collect all the documents in the Prologue
Kill 350 enemies with the Old Axe
Find 5 secret rooms
Kill 10 Spitting Spiders
Kill 400 Walking Soulless
Use a Device
Finish a level with only melee weapons
Complete the Demo on Nightmare difficulty
Complete the Demo on Hard difficulty or higher
Complete the Demo on Medium difficulty or higher
Survive the whole Prologue on NIGHTMARE difficulty with the same volunteer
Finish a level without taking any damaged on NIGHTMARE difficulty
Kill the Hand in less than 20 seconds on NIGHTMARE difficulty
Death count: 10
Death count: 1
Complete the Demo
Complete the Demo on Easy difficulty or higher
Kill her with her own weapon
Leaving Building C
Deploy a Gadget
Kills count: 50
As big as an elephant
Find 5 documents
Kills count: 15
Rounds fired: 200
Rounds fired: 100
Upgrades Cost: >1000