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