Ending D: First off, make a save on any playthrough before you destroy the Aerie if you havent collected eagle eggs to use if you haven't gotten the upgrade all weapons achievement and plan to get it- you cannot get eagle eggs anywhere besides the Aerie collection spot under the chief's house. (Update: the may 12th DLC has eagle eggs in the third section of it that I got 2 out of 3 runs through it. the DLC is basically like playing the game on mind altering drugs and fighting stuff way more brutal than anything in the main game. it's not very long, and I didn't know what to expect going into it, but now, even without it directly having any achievements, it was worth the money for the fun it provides. the different armor models you can choose are interesting and also change the rest of your party members armor, and also uh,.... turn all the red orb projectiles into emil's head. I'm not even kidding. i just dont know what to say about that.)
Now then: the best way to go about triggering ending D is to make a separate save at the mailbox on the roof of the Lost Temple before you break the final seal on your way to get Ending C. This will save you an extra part II playthrough. Here's how to do it. Proceed to complete your run and get Ending C (do NOT choose the sacrifice option for ending C, and for ending C you need all weapons collected for the alternate execute option to be available- SEE THE ENDING C GUIDE below for further details- if you mess this up you could be SEVERELY screwed). Again, the execute option will only be available if you have all the weapons collected. Otherwise you only have the choice that leads to ending D which will wipe your data, so it's easier to do C first.
If you are missing weapons, refer to the solution I wrote up for the "Weapons Collector" achievement here:
After watching Ending C, *DO NOT SAVE OVER YOUR PRE-BOSS SAVE* that you made on the roof of the Lost Temple (don't save over your Aerie save either if you haven't backed it up yet and need it). Save to the other slot and exit back to the main menu at which point your ending C achievement will pop. Now, load up your pre-boss save and just run the last area again and choose the sacrifice option at the end to trigger ending D.
Ending C procedure:
side note for the time trial for the boss involved in ending C and D:
The The Strongest Bond achievement in NIER worth 75 pointsDefeat a certain boss within three and a half minutes.
WARNING: CHOOSING THE OPTION FOR ENDING D WILL ERASE ALL YOUR SAVES!!! Dont have your back-up memory stick or whatever plugged in either, when you make the final decision, just to be safe. It makes a BIG point of wiping everything out- you'll see what I mean.
Soo, unless you don't care about losing all your data, you need to back up your saves on a separate memory unit before watching ending D. If you back them up you'll be able to finish the harder grind achievements that you probably did not finish yet like Man of Means and Fully Upgrade all weapons. If you want to get 100% completion and haven't finished everything else, then you'll have to play the game all over again to tie up those loose ends if you didn't back your saves up.
Further step by step Ending A,B,C, and D guide: (HIGHLY recommend you read this)http://www.xbox360achievements.org/forum/showthread.php?t=22...