Spec Ops: The Line
50 Achievements
15-20h
Sierra Hotel
Complete three chapters in a row without being killed or reloading a checkpoint.
10.4%
How to unlock the Sierra Hotel achievement in Spec Ops: The Line - Definitive Guide
This achievement is very easy on Walk the beach difficulty, i got it while grinding out the shotgun achievement without really trying. Just don't let the shotgun enemies get too close and you're good to go.
I guinea pig tested myself to see if it worked finishing the 2nd chapter and starting up the 3rd mission the next morning (I didn't die or restart CP in any of the three) but no cigar. Just a warning if you try on the later missions which are a tad longer to complete which makes you take breaks etc .....
So, I restarted a whole new campaign, and after beating the first three chapters... beep-bop, achievement unlocked!
Thus, whether I experienced a glitch or not, I recommend you to start a new campaign when going for this achievement.
So just load up a new game on easy, and carefully play through the first three chapters, should be no trouble at all. Remember to use cover and squad orders, because one mistake and you will need to start over!
My advice is to complete the game to unlock all the difficulty achievements first. If you still haven't unlocked this achievement, just select the easiest diffculty and start a new campaign, being very careful, and unlocking it during the first 3 chapters.
Unless you have superior luck and the shooting skills of a God then you more than likely will not get this trophy during your "hard" or "very hard" playthroughs. So, after you have finished your hard mode playthroughs load up the game from the first chapter on "Walk on the Beach" difficulty and carefully make your way through the first three chapters. By now you should understand the game and how to avoid pointless deaths; this trophy should cause you no problems especially on this easiest difficulty setting.
If needed you should combine this step with the trophy All You Can Be.