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