PigStor(i)es is a free clone of old good Sokoban from eighties. This version is variant played on hex board so it's hexoban.
There are 20 levels with varied difficulty.
Difficult ones designed by David W. Skinner & Aymeric du Peloux.
Nice music you can listen to is Chicken by Jumbo Jazz.
There is port for Linux and Windows so you can try it on a less mobile device but maybe with bigger screen.
Pigstor(i)es can be also known as pigstories, pigstores, pig stories, pig stores.