Hey,
Technically this achievement is missable if you choose the wrong answer at the start of the game.
When you are choosing your character (the choice won't influence this achievement). You are asked about hiking preferences. These are actually the difficulty settings. They translate as follows:
1. like climbing a mountain = Normal
2. like going on a hike = easy
3. like going on a walk = very easy
So be sure to take " like climbing a mountain" to start the game on normal. You will be rewarded with all three difficulty related achievements at the end of the game.
If you are new to the game this will probably be the achievement you will be going for. There is no need whatsoever to play this game in easy or very easy first because the game itself is not that hard (especially if you are playing with Jill first).
If this is your first attempt at RE take your time with this first playthrough. Explore, enjoy the story, get scared (by the jump-scares or the controls, it's up to you ;-)).
I strongly suggest you do this playthrough with Jill (easier boss battles, more inventory, easier accessability to guns BUT takes less damage) and make sure you don't miss the following missable achievements:
1. "Trust him"
2. "Sorry about the wait"
3. " I am a member of S.T.A.R.S"
Please refer to each achievement's guides and solution if you need help with those.
If you have problems with any of the riddles please refer to the videos below. I could not find any non-speedrun videos but as far as the riddles are concerned everything is covered. One video refers to a playthrough with Jill, the other to a playthrough with Chris.
Video credits go to: SSoHPKC (Jill) / Carcinogen (Chris
Hope this helps you guys ;-)
Any improvements or questions? Let me know in the comments!