I want to create reward website like swagbucks, a microtask website

Hello, I am looking to create a reward website similar to Swagbucks, where users can participate in various activities and tasks to earn rewards. Specifically, I would like these activities to include completing offers. I envision the reward system to be a variable point system, meaning that certain tasks will earn more rewards than others. Finally, I would like users to be able to redeem their rewards in the form of gift cards.