I normally don't play mobile games but I love this anime so much I had to give it a try. The game is your average stamina based Gatcha game with in game purchase. You have a certain amount of stamina (20 to start with) every day that you use to take missions which cost stamina. You start off with just Bell Cranel and Hestia but you can get pretty much every character from the Anime by using the Gatcha slot machine. One spin is 40 crystals but for opening week they are doing 11 spins for 400 with guaranteed rares. Just doing the daily and intro quests alone you will earn so much you won't have to worry about paying for a long time if you plan only playing for a few minutes a day which is what I have been doing.
The game is half visual novel and turn based RPG (similar to Final Fantasy 6). The visual novel part is what has impressed me the most so far. The art is beautifully done and there are even animated cut scenes and stills from important parts of the anime. All the voice acting is Japanese subtitled and it appears to be newly recorded instead of re-used from the TV show. As someone who is eagerly awaiting the next season this is a good way to scratch the itch. The games covers both the original Anime arc and Sword Oratario as well as additional character side stories.
Now if only they could take this engine and make an Overlord or Konosuba game I would actually put real money into it.