what is the best way to publish game ?

hi my friends . first of all sorry for my english !
today i create 80% of my new game it is my first game that i want to publish in google play and i am very happy LOL :slight_smile: . this game is for android in now and i want to build it for ios in future !
i have 2 important question !
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1-> my game is not free . it have 120 levels but i want to 20 levels of my game become free (do you understand my point ? :confused: ) indeed i want to put it free for 20 levels like angry bird and after win in 20 levels player must buy my game for all the levels can i do in ue4 ? can you help me ?
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2-> if i publish this game in my google account i am not sure that people buy it because this is my first game but my game is not bad i use and create very beautiful material and particle system and my game is very fantasy . are there other way to publish my game ? are there any studio for publish my game ?
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thanks

There are whole books about this subject.

I dont understand your mean . books for UE4 tutorial ?

Like that one.

Thanks but i can not use ad in my game also i can not use in game billing !

Hi Amir,
I would recommend that you publish 2 versions of the game:

  1. A free version with only 20 levels available.
  2. A paid version with all 120 levels.

Cheers