Great job, man.
In fact recently i also have the same idea that port the existing YGOpro to Android, but i just start up and don't have much time on this :(
there are some question about your work: do you port the YGOpro native C++ code that using NDK or you just rewrite it in JAVA. Looking at your app, the rendering style is quite consist with the origin YGOpro, so if it is NDK approach, i guess there is not much extra effort on network-play mode, and everything in YGOpro is already done except AI mode.
maybe i can lend a hand if you still need some help, and i also look forward to running YGOpro on my phone and play with my friend anywhere