I have a question regarding for the game app and in business. You see, I decided to publish an app to Google Play. When I published it, does this app automatically declared that this app is copyrighted or copyright protected by the publisher and creator like me itself or not? If not, does it have to seek something or required to register this app for copyright authentication via online or at office or not?
The moment you create a creative work, you automatically have an exclusive copyright on it. This is guaranteed by various international copyright treates (like the Berne Convention) which are recognized by almost all countries worldwide.
In some jurisdictions you can register a copyright for a work (in the USA, you can do so at the United States Copyright Office), but this is optional and not necessarily required to enforce your rights in court when you have other prove that you created the work.
An explicit copyright notice ("Copyright ©2013 John Doe, all rights reserved") is not required either. It is just used as a friendly reminder to people that you are the copyright owner and that you care about your copyright. But such a notice is not required to enforce it, should someone violate it.
When you publish something on google play, you give google a non-exclusive license to distribute your software (otherwise they wouldn't be allowed to publish it). Non-exclusive means that you retain the copyright. You can still publish it yourself, license it to other entities and sue entities which distribute it without your permission.