All shutting down Google+ Games means is that the integration of web games with the Google+ UI is going away in favor of piecemeal integration. Google+ Games is essentially the old Facebook model that even Facebook-linked games are using less, the new model (supported by Google Play Game Services, Google+ SSO, the Google+ Moments API, etc.) is of games (quite often native mobile games rather than web games) that interact with a support platform through a sign-on API, cloud services that provide saves/multiplayer toos/leaderboards/acheivements, and systems that allow integration with social network news feeds.