We do a lot of work for top agencies that we can't display in our online portfolio due to client confidentiality - this is one such project!
In 2011 we built a very high profile competition app for a household name. The app was incredibly popular and far exceeded ROI expectations - so we built several more for the same brand over the following year! The app allowed you to enter a competition daily, and allowed you to get extra goes by inviting friends - but thanks to clever tracking you only got the extra goes if the friends actually excepted your invitation! Prizes and runner-up vouchers varied each day, with any prizes not won given away at midnight to people who'd played that day.
It was an extremely sophsticated app - if you need something similar please do get in touch!