I recently started playing this game. I've been waiting so long to play it and it finally came out in English.
It's free on Google Play and whatever Apple's equivalent is 8u

It was first announced in 2011 that a Gaiden work of Puella Magi Madoka☆Magica" would be developed. On September 22-25, 2016 the game was officially announced at the SHAFT 40th anniversary event "Madogatari" . Atsuhiro Iwakami, the producer of the original anime said "Since it seems that it will take some more time until the anime's new work, the idea that I want to make a title that "Madoka Magica" is active will work."

Ume Aoki was responsible for the design of the original character that serves as the game's protagonist, as well as designing more than 10 new and original characters for the game. Gekidan Inu Curry is also responsible for the designs of the new witches. In addition to this, Shaft has produced the opening animation and magical girl transformation scenes.