Found out the issue. Connecting the phone to the computer and running logcat after setting up adb and related system drivers, I was able to resolve the immediate crash upon startup.
Here's part of the logcat:
12-03 20:58:55.932 12946 12946 W ResourceType: Invalid package identifier when g
etting bag for resource number 0x00000000
12-03 20:58:55.944 12946 12946 I Prime31 : found Activity proxy class: class com
.prime31.GoogleCloudMessagingPlugin
12-03 20:58:55.944 12946 12946 I Prime31 : found Activity proxy class: class com
.prime31.PlayGameServicesPlugin
12-03 20:58:55.945 12946 12946 I Prime31 : onCreate. calling through to init
12-03 20:58:55.985 12946 12946 W PopupManager: You have not specified a View to
use as content view for popups. Falling back to the Activity content view which
may not work properly in future versions of the API. Use setViewForPopups() to s
et your content view.
12-03 20:58:56.331 12946 12946 D AndroidRuntime: Shutting down VM
12-03 20:58:56.334 12946 12946 E AndroidRuntime: FATAL EXCEPTION: main
12-03 20:58:56.334 12946 12946 E AndroidRuntime: Process: com.nexonm.dominations
.adk, PID: 12946
12-03 20:58:56.334 12946 12946 E AndroidRuntime: java.lang.Error: FATAL EXCEPTIO
N [main]
12-03 20:58:56.334 12946 12946 E AndroidRuntime: Unity version : 4.6.7p1
12-03 20:58:56.334 12946 12946 E AndroidRuntime: Device model : Huawei Nexu
s 6P
12-03 20:58:56.334 12946 12946 E AndroidRuntime: Device fingerprint: google/angl
er/angler:6.0/MDB08L/2343525:user/release-keys
12-03 20:58:56.334 12946 12946 E AndroidRuntime:
12-03 20:58:56.334 12946 12946 E AndroidRuntime: Caused by: java.lang.RuntimeExc
eption: Unable to start activity ComponentInfo{com.nexonm.dominations.adk/com.ne
xon.dominations.MainActivity}: java.lang.SecurityException: getDeviceId: Neither
user 10119 nor current process has android.permission.READ_PHONE_STATE.
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.app.ActivityT
hread.performLaunchActivity(ActivityThread.java:24 16)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.app.ActivityT
hread.handleLaunchActivity(ActivityThread.java:247 6)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.app.ActivityT
hread.-wrap11(ActivityThread.java)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.app.ActivityT
hread$H.handleMessage(ActivityThread.java:1344)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.os.Handler.di
spatchMessage(Handler.java:102)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.os.Looper.loo
p(Looper.java:148)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at android.app.ActivityT
hread.main(ActivityThread.java:5417)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at java.lang.reflect.Met
hod.invoke(Native Method)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at com.android.internal.
os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.j ava:726)
12-03 20:58:56.334 12946 12946 E AndroidRuntime: at com.android.internal.
os.ZygoteInit.main(ZygoteInit.java:616)
:: TL;DR ::
READ_PHONE_STATE permission was not given to the app, hence the crash.
In Marshmallow, set the app's permissions via
1. Settings > Apps > DomiNations > Permissions
2. There are three individual permissions Contacts, Phone, and Storage.
3. Allow all three.
4. Launch the game and connect your Google Play profile
5. Profit and have fun playing it.
6. To the game devs, if you need an outside tester, I'll be available
I'm a programmer and familiar with all this. A normal user with a high-end phone shouldn't go through hoops like I did.