This is not too hard to achieve. This game is quite short. You'll pop this at the end of Chapter 3 part 5.
So this isn't really a guide so much as it is a piece of advice for people who may encounter the same issue I did which was not popping the achievement at the end of the game.
Now the only issue I had with this achievement was that I started the game on Hard and did 3-4 levels on Hard before dropping the difficulty to Normal. In order to pop the achievement I had to go back and play through those levels again and complete them on normal. Simple as that.
Hope this helps someone out as I ended up replaying the final level a few times more than I'd have liked