I love strategy games. Recently I got back into chess, after a decade long pause.
I tried a bunch of chess mobile apps and settled on one I think is the most comprehensive, totally free and without ads. It's called lichess.org - you can play on the browser or mobile app.
If you have never tried chess, this app/website has all you need to get started: lichess.org/learn
It has a staggering amount of content and features to suit all levels. Lots of training exercises, puzzles and videos. Live only playing and watching. It stores all your games and has the capability to analyse them and point out blunders so you can learn from your mistakes.
I particularly like the lichess TV where you can watch a live feed of the top rated players, allowing you to learn with the pros : )
If you fancy a game hit me at: lichess.org/@/veganic