The Google Play Games development environment is still in closed beta, but this doesn't stop you from updating your game to work on a PC. Your game will need to:
- Run in an Android environment
- Be built for the x86 or x86-64 architecture
- Run on PC class hardware
- Require a mouse and keyboard
- Work with a large screen
All of which you can test by using the developer emulator or on a Chrome OS device. This will give you the chance to make any design or tooling changes needed to make your existing Android game work well on a PC.