FF Brave Exvius is a F2P mobile game, pretty good. Microtransactions of course, but they're pretty nice to new players, and you can build pretty good parties, without requiring 5 star bases. I only played Record Keeper for a little bit, before wanting to move on. Too many tutorials for my tastes, I wanted something quick and easy to pick up, which fits FFBE, but it also has challenging fights, when I feel like doing those.