Hi, I'm a full stack developer. I want, with a friend of mine, to develop a multi platform mobile game. It will have online matches, a scoreboard, a shop. Something like "clash of clans" or any other online game. 
I read about unity, phaser, unreal engine and many others technologies I have never used ... But I don't know which one to choose and start learning. Do you have any advice? Any articles, guide about game dev? Someone who was in my situation has suggestions, or just tell his story?