Build gaming app like HAGO, POKO

Hey, we already have an android app, it will conduct a tournament for all users, based on winner we are giving real money, currently, our main competition is a text-based game - last comment writer is the winner. Now we are planning to extend our application. We plan to build an app like Hago, Poko, both apps have lot of features, chats, broadcast and more, We want only the gaming part. We want to integrate lot of games into our existing native android app. We will conduct tournament on those games. What we need from you. 1. You need to build one architecture for us to adding games. 2. Which is the best html5 games or android games or unity games? 3. For each game do we need to develop our own or any marketplace available for selling games, if yes we need to buy and integrate into our app very easily? 4. Initially, we need sheet fight, archer, and ludo the same as Hago, how to integrate and conduct the tournament. We already have a payment solution, don't care about that. Major point: If the user going to any game the first time, that time only those game asset needs to download in your mobile because we plan to add more than 100 games. Finally, we need to have 1 app that will have 100+ games. if you are suggesting to purchase the game apps from somewhere we are ready. If anyone experiences this type of application, please place your bid.