Hi,
This sounds like an exciting opportunity and idea. My milestones reflect how i see the functionality you expect. At a high level, the application will allow users to register, challenge other members for a trivia and once started it will measure their score for a pre-defined set of questions, at the end they will be shown the result.
The web application will be responsive so it can be seen on mobile devices as well.
I presume you will provide the infrastrcuture/servers where this will be hosted. Since the volume might be huge we might need a SQL (mariadb) and NOSQL (cassandra) databases.
Thanks
Mahesh