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