They do not need to be fully decentralized apps. Main requirements:
(1) Integrate the Kin SDK into your mobile application and move to production.
(2) All apps need at least one social feature using Kin (leaderboard, tipping, group challenges etc.)
(3) Go live to either the Google or Apple app store and submit through the Devpost submission process.
For the full rules see https://kinchallenge.devpost.com/rules
Production does require the use of one of our server SDKs using either python on nodejs. We also have a python bootstrap docker image that you can host on AWS or heroku and it has everything you will need to run in production just by deploying it and adding a bit of configuration