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