GHOST 1.0

Not too hard if you know what you're doing. I don't know if it counts if you start a New Game+ with your previous skills and don't choose any skill in this new run but finish the game once or twice so you know what to expect, then start a fresh new game. If you think you had a trouble in a room, just save and quit and keep trying. it's all about keep trying until the end, you'll only miss the Double Jump skill who can save a lot of trouble and can be used to skip some routes but nothing terrible. Also take extra caution at Chunker as you can't extra jump out of the pits this time (without Double Jump).

Play on easy, you don't need to make it harder on yourself for this, try not do unlock any other achievement while doing this one as other achievements can make you lose your focus/make it harder on you, keep trying and the achievement will be yours.