Startup Idea : App that encourage gatherings and events

For example, someone wants to host a dinner gathering, he uses this app to send invitations to his frens, provided they have this app too. He sets the date and place, and on the day itself, whoever turns up at the place for dinner will receive 5 pts, and the host will get 10 pts etc. Attendees Wil Ned to check in using the app to take attendance. Points can be used to redeem rewards like vouchers or cash.