Need help Debugging a apk+api

Its from android game it uses a api, i need some help for debug the http calls it does, i have already done some of work.

I can help with that. Shoot me a PM. If you just wanna know how to my recommendation is to use BurpSuite Community Tool
and connect the proxy server using Android WIFI settings (Guide) then you will be able to intercept all the network requests your phone does and you can filter them to target a certain apk.