Game is overly complicated with too many different types of unusable items and resources needed for different things. Inventory list will show item affiliations but doesn't when using as upgrade material. Rare unit drop rate is pathetic as I'm getting the same 5* units all the time, and you can't use those duplicates as promotion material. It's super power hungry and gets extremely hot, limiting play time to a max of 5-8 minutes before my phone starts overheating and too hot to touch.