A total of 26 endings you will encounter in NieR Automata. The endings are named with letters from A to Z. If you play the game for the first time, you will activate Ending A. At the second pass, you will activate ending B. If you have completed the first ending, then your game save shows you Ending A. So you can always see which ending you have achieved with game save.
Of course, you don’t have to play the game 26 times to activate all endings and ultimately all achivements. After you have completed the NieR Automata three times, the chapter selection is enabled. Now you can select the respective chapter and the character to be played. For this reason, the following table also contains some of the chapters you need to select. In addition, you should work a lot with manual game save.
Ending A - Run Automata for the first time.
Ending B - Run Automata again for the second time.
Ending C - Run Automata for the third time and select A2 as character for the final boss. (Kill 9S for this.)
Ending D - R run Automata for the third time, and select 9S as character for the boss. (Kill A2 for this).
Ending E - Activate the end C or D and select 9S or A2 as they stand opposite each other. (After the credits, you must answer yes to each question.)
Ending F - Chapter 01-03, 2 - Let three minutes elapse in the Prolog when 9S in the fight against the Goliath tries to re-activate its operating system.
Ending G - At the beginning of the second round with 9S behind the crate, jump onto the crane and then jump to the next platform. (Do this as soon as you can control 9S for the first time.)
Ending H - Chapter 05-03 - Don’t go to the flight units in the city, if the opponents attack the ruin city, but take the path to the amusement park.
Ending I - Chapter 08-01-2 - Leave the area instead of taking care of the ground on the ground - after killing Adam.
Ending J - Chapter 09-02-3 - Attack the priest after showing you the way through the factory.
Ending K - Eat a mackerel. (Fish one or let one of the NPC give pop.)
Ending L - Chapter 10-02 - Go to the crater in the center of Ruin town when the fight against Eva starts.
Ending M - Chapter 4-03 - Go to the big bridge in the city, rather than help Pascal.
Ending N - Chapter 07-02 - Destroy all machines in the Machinery.
Ending O - Chapter 11-04 - In the third pass, leave the area instead of hacking as 9S in 2B. (When the Androids are home to the virus.)
Ending P - Chapter 11-06 - The operating system of 2B with the virus to 100 percent contaminate.
Ending Q - Chapter 11-07 - Leave the area right at the beginning of the chapter instead of going to 2B.
Ending R - Chapter 14-05 - Destroy the last machines in the abandoned factory as A2.
Ending S - Chapter 17-01 - Leave the area, instead of fighting with Devola and Popola.
Ending T - Destroy the BS chip. (This is your operating system, which can be found in the skills menu.)
Ending U - Start the self-destruction in the bunker. (On the PS4: with L3 and R3.)
Ending V - Chapter 17-01 - Don’t hack the tower in the crater after fighting with Devola and Popola.
Ending W - Chapter 01-03-2 - In the Prolog (Tutorial) die.
Ending X - Chapter 11-06 - Leave the area, rather than as A2 to help the YoRHa.
Ending Y - Destroy the secret end boss. (After the fight you can do nothing more, but you just have to watch.)
Ending Z - Pascal at the first meeting as A2 kill.
So in the end, you just have to run through the world of NieR Automata just as a malicious Android, in order to activate almost all the endings. If you don’t help, the game comes quickly to the end. You will get the shortest playing time with ending W.