It's called Metal Waltz in Asia, Panzer Waltz in the West.
It's Android/iOS only, english version available on Google Play Store or the game website.
- Cool background music;
- Story mode: 24 chapters, each with 4 maps and 1 special operation;
- PvP mode: setup an attack squad to battle against other players, setup a defense squad to protect your resources while you're offline;
- Event mode: special operations only available at certain hours during the day;
- No limit to how many tank girls you can have, but you can only have 1 of each;
- Hundreds of tank girls to get, from different nations and tank classes;
- Map terrain and combat area size on the battlefield affect how your girls perform: from wide grassy plains to snowy rocky mountains to swampy valleys to cramped city streets;
- Tank girls and equipments can be obtained through drops, crafting or gacha system using ingame currency;
- Several tech trees for different ammo types, tank engines, armor and chassis upgrades;
- Upgradeable HQ base, gives more resources and gameplay functionality the more developed the base is.
Want to give it a try? Download the app, install, let it update, register an email and password, and you're good to go. Requires internet connection to play.
Want more info? There is an english speaking community wiki, search for Panzer Waltz or Metal Waltz, you'll find it easily.