Here is the full list of all 42 HALF DEAD 2 achievements.
Win five times in cooperative mode
Use bandage hundred times
In deathly room die from lasers
Discover seven hundred ten rooms
In deathly room die by suffocation
In deathly room die from sculls
In deathly room die from shark
Find five hundred traps
Fahrenheit 451
Discover two hundred rooms
Find two hundred fifty traps
Win once in PVP mode
In deathly room die from buckshot
Discover hundred rooms
Find hundred traps
Discover fifty rooms
Win once in cooperative mode
Find fifty traps
In deathly room die from turbine
Find twenty traps
Die from crocodile
Find ten traps
Discover five room
Find five traps
Win five times in PVP mode
Win ten times in PVP mode
Win ten times in cooperative mode
Win twenty five times in cooperative mode
Install wooden plank fifty times
Break lighter fluid fifty times
Explode dynamite fifty times
Throw neurotoxin fifty times
Use first aid kit twenty times
Use pills fifty times
Use flashbang grenade fifty times
Use impulse grenade fifty times
Use electroshock to modify weapon twenty five times
Use nails to modify weapon twenty five times
Use poison to modify weapon twenty five times
Use torch to modify weapon twenty five times
In deathly room die from chain
In deathly room die from teddy