A long running sweepstakes for Riunite integrated as a Facebook app.
A match game built in React.js and React Router. A hash router was used to control which view of the game was presented to the player.
When picking cards the game had to verify if it was the first of second card in a potential match. If it was the second it would compare it to the first to see if they were the same type but not the same card. Consecutive correct matches increased a players multiplier.