I tried your game and I think it needs to be much improved.
However you have recreated an evocative atmosphere, I suggest you improve:
Menu: also minimal but important
Controls: maybe with a custom interface.
Info: it is not clear what to do and what can be done in the game.
View: character too far away.
Camera collisions: no good at all when camera enter in the ground.
Audio: ok for footsetp but I feel the lack of music or the effects of the environment.
Size: optimize your content, the size is really too big
Ultimately I have to tell you that the type of game you have chosen to develop is not the most requested in the stores, if you want to make significant numbers I suggest you bet on simpler and less ambitious games.
Said this I’m asking you some questions:
what version of unreal did you use to generate the build?
Have you had any problems with the sdk 26 target?if yes, how did you solve it?
Finally, for AdMob did you use the default blueprint nodes or some external plugins?
Thanks and sorry for my English