Here is the full list of all 71 Heart&Slash achievements.
CREATURE OF THE NIGHT!
BEAT QUASSY AND UNCOVER THE TRUTH
DISRESPECT THE AUTHORITY
DISPLAY YOUR COMMITMENT
DEFEAT TWENTY FIVE SMALLBOTS IN THE CITY
UNLOCK ALL BLADES
DEFEAT ONE OF EACH ENEMY CARRYING A BLADE OR A SAW
DEFEAT TEN WORMS
UNLOCK ALL AXES
DEFEAT ONE HUNDRED SCAVENGERS
DEFEAT YOUR FIRST MAGNET
FIND SLASH IN THE OUTSIDE WORLD
LONG LIVE THE QUEEN
DEFEAT FIFTY C.O.P.S. ENEMIES
DEFEAT FIFTY LASER ARMED ENEMIES
DEFEAT FIFTY SMALLBOTS WITH A BACKPACK
SURVIVE FIFTY ARENAS
REACH FIFTEEN HEARTS OF MAX HEALTH
DEFEAT YOUR FIRST C.O.P.S. FLASHBANG
EQUIP YOURSELF COMPLETELY
UNLOCK ALL FIST BASED WEAPONS
COMPLETE ALL THE QUESTS IN THE FACTORY
HELP SLASH EXIT THE FACTORY
BAT FIFTY MISSILES
DEFEAT FIFTY ARMOURED ENEMIES
HAVE YOUR ENEMIES DEFEAT TWENTY OF THEIR OWN
USE YOUR HEAD AND SAVE SLASH
DEFEAT ONE HUNDRED SMALLBOTS
DEFEAT FIFTY ELITE ENEMIES
DEFEAT ONE HUNDRED BIGGRUNTS
DEFEAT FIVE TRIPODS
DEFEAT TWENTY FIVE LASER ARMED ENEMIES
DEFEAT ONE HUNDRED NIMBLEBOTS
JUMP A THOUSAND TIMES
DEFEAT TWENTY FIVE ARMOURED ENEMIES
SURVIVE SLASH'S CHALLENGE
DEFEAT THE GUARDIAN
EXPLORE ONE HUNDRED ROOMS
DEFEAT ONE HUNDRED FLYBOTS
DEFEAT FIFTY SHIELDED ENEMIES
SURVIVE THE DOCTOR'S CHALLENGE
DEFEAT TEN LASER ARMED ENEMIES
DEFEAT YOUR FIRST TRIPOD
SURVIVE TEN ARENAS
DEFEAT TWENTY FIVE SMALLBOTS
DEFEAT TWENTY FIVE BIGGRUNTS
DON'T BE MEAN
DEFEAT TWENTY FIVE NIMBLEBOTS
BEAT THE UNBEATABLE
DEFEAT TEN SMALLBOTS
DEFEAT TEN BIGGRUNTS
SURVIVE FOR TWENTY MINUTES
DEFEAT TWENTY FIVE FLYBOTS
UPGRADE A WEAPON AND LET THE GOOD DOCTOR KNOW
DEFEAT TEN NIMBLEBOTS
DEFEAT YOUR FIRST SHIELDED ENEMY
DEFEAT TEN FLYBOTS
SIDE WITH SLASH IN THE FIGHT AGAINST QUASSY
TOGETHER WE RISE
CLEAN THE REMNANTS
DEFEAT ALL BOSSSES IN THE FACTORY AND THE CITY
DEFEAT TWENTY OF EACH DOG'S PARTS
DEFEAT TWENTY FIVE TRIPODS
DEFEAT TWENTY FIVE ENEMIES WITH A BACKSTAB
DEFEAT TWENTY FIVE WORMS
DEFEAT FIFTY WORMS
DEFEAT FIFTY SMALLBOTS WITH A FIRE BACKPACK
DEFEAT FIFTY SMALLBOTS WITH A FREEZER BACKPACK
FINISH A LEVEL UNSCATHED
BEAT QUASSY WITH A FULLY UPGRADED RUBBER DUCK
BEAT QUASSY WITH THE PROTOTYPE