1.- Must play in Story Mode (yeah some people were trying in time attack)
2.- You can use any weapon (Based on the RNG I just used whatever at hand, I beat the final boss with a SMG lol)
3.- Partners - Get one as soon as possible, although it's possible to get the achievement with any partner I strongly recommend to go for the Advanced Sniper Rifle Girl during the first section of the game (guarding the exterior gate) if not I suggest a restart to save time and make your life easier, be aware she is a rare drop and on the run I got the achievement I was never able to upgrade her card as she never showed up again, yet at Lvl. 1 she is a boss killer throughout the entire game
4.- Dormitory choices - Always take a shower at least the end close of the game when the two stats it augments should be almost at maximum
5.- Card draws - Never pick chance cards - Trade-off cards are your best friends - Defense and repair cards take priority
6.- Early game barricades and spikes are good for crowd control, experiment with them placing them away of the gate,
7.- All special one times buffs such as the cutting laser , the carpet bombing etc... were not worth the money on my runs for this achievement
8.- Sometimes not picking a card is the best choice. =)

1.- Most comments and Guides state that to reach the good ending you must not allow the gate to reach the Yellow bar of health
FACT --- At the middle of the run (Inner gate) on 2 different rounds I went all the way to Red and still got the achievement. The reasoning I have for this is that the game actually counts the overall cumulative damage received per every section of the game. how did I reach this conclusion?
--- The battle report after the first section of the game (Outer Gate defense) measures your performance like this:
And even then I went into Yellow in the first 40 days twice.
Therefore I recommend that if you do not get a PERFECT GUARD rating Restart the run







2.- Number of retries must be 0
FACT --- Yep that is a Fact (I failed to get the achievement even with one retry)

3.- Shotguns are the best
FACT --- As I mentioned weapons are RNG however I found to my taste that shotguns are not good for crowd control with over 20 enemies closing on the gate on screen, and it becomes worse if Bullet concentration is high as it narrows the bullet spread therefore hitting less enemies, I personally find myself comfortable with LMG (Due to the large magazine and damage output) in the end is up to your taste and RNG whatever weapon you pick just Git Gud with it

4.- The Grenade Launcher sucks
FACT --- Yes it does for the ends of this achievement

5.- Help is on the way...
Yes it is but only if you get this achievement

1.- There is nothing much to say about the actual game play here besides what is already listed above, it is a matter of trial and error, in case you are wondering for me it was on my 4th run following the advise I provided here.

2.- Enjoy the good ending and let's keep our fingers crossed for a sequel. =)

SPOILER