Can anyone help me on how to even start this project, please?

Hey guys me and my friend want to build a game for phone devices like tanoth or ikariam or erepublic but we dont know where to start. We arent even sure if UR is the proper engine we should use and i cant figure out what other games similar to our idea use. What would u say guys is this the engine and do you know any guides or anything that might help or what template should i even use :D. I’ve made my own MMO project on Unreal and it was working with enemies quests different levels but that was just for fun. Here we want to actually start working on a game for the app store and make some dough :smiley:
Thank you for reading and helping out <3

Did you make your game on Unreal Game Engine? if yes do you you want to proceed with the same game engine or do you want to try other game engines like Unity 3D.