I finally got around to playing and finishing the game.  Music is great, story is engaging, and there are some fun game mechanics I want to remember.

Various Game Types Combined Into One

Early on when player is piloting an air frame that transforms into a robot, and after the playable character gains hacking ability, the game is presented as a bullet-hell shoot-them-up mini game similar to Geometry Wars.

The rest of the game is like a 3D beat-them-up with combos and launch moves, plenty of platform jumping and running, role playing weapon/armor/ability upgrade and management elements.  The perspective switches get really confusing (sometimes character move in 2D plane, but camera shifts).  I was trying to read the dialog bubbles while screen is half-filled with enemy bullets.  It shouldn't have worked with so many types of games combined into one.  

Music

Music in this game has multiple tracks that are remixed based on character location and story progression.  There is a jukebox in game that has a really clunky menu interface but allows easy sampling of different remixes of background music.

When game switches between free-roaming combat and hacking mini-game, the music instrument changes but the tune remains similar.  It's really neat.

Upgrade Mechanic

To improve character stats, you select which chips you want to install.  Each chip requires certain number of slots, and total number of slots available can be expanded up to a fixed maximum that behaves like memory storage in a computer.  As you add and remove chips you leave these gaps just like memory fragmentation in programming.

Much of my time was spent selecting chips to help me survive a boss fight or extract maximum reward from running around in the game.  Which chip I select really makes a big difference.  For example, it is possible to have healing items trigger automatically when my health drops below critical level.  If I don't need to see my health bar, I can remove that chip and use the slots for something else.  There are chips that change combat by slowing down bullets when they are near my character.  Chips that reveal items on the map, where to fish, etc.  I can stack some of the chips to increase the effects without having to buy or farm higher level chips.

If player doesn't want to do the math or fiddle with chips, the game can automatically optimize for a playing style.  It also helpfully provide 3 save slots for different chip configurations and a way to compact the install chips so that there is contiguous space at the end for me to put more chips in without having to relocate installed chips myself.

At least for me, this is an enjoyable mini game all by itself.

Adjustable Difficulty

The game difficulty can be adjusted dynamically.  If a player doesn't want to fight and select easy difficulty, the upgrade mechanic allows these "auto" chips to be installed so that the game engine will carry out the fighting, shooting, and dodging actions automatically for you.  I guess it is helpful if you want to see the many endings or just the stories in this game.  It immediately makes the game as accessible or challenging as player demands; again I think it is a neat design.

The Endings

After playing for 50+ hours I panicked when I got to one of the endings that, if I wanted to continue with my choice of giving back to the community, basically means I'll never play the game again.

After searching online and looking up YouTube video clips, I found out there are many many endings in this game, and some of them are only accessible if I make some really messed up decisions.  So NieR: Automata is definitely a game you'll be playing over and over again.  It's a good thing it is so well designed.  

And it will delete your save file, if you end up following through on your decision to give back to the player community.  Make my decision that much more meaningful.