Google Plus was launched in beta trial a month ago but still there are no APIs available for developers. Developers have made many applications which allows a user to post directly from Google Plus to Facebook & Twitter, external services which allows users to choose an easy to remember & share vanity URL for Google Plus and few chrome extensions e.g which allows users to show Twitter and Facebook feeds on Google Plus profile.
All such applications have been developed without using Google Plus API and hence have restricted access to your Google Plus profile data. To make really useful and highly interactive apps like games, developers needs to have access to Google Plus API which are not yet released by Google. If you are interested in becoming a Google Plus developer and want to develop games and other apps for Google Plus, you can submit your request to Google Plus by following the below steps. Once Google Plus will be launched publicly and releases APIs for developers, you’ll be among the first ones to get the opportunity to fulfill your dream of becoming a Google Plus developer.
How to become a Google Plus developer?
Go to Google Plus developer signup page to register yourself as a developer in Google+ Project. Sample form is shown below where in you can fill in your details.
Once you are done filling up the form , hit the submit button and confirmation screen as shown below will add you in Google Plus developer group.