var server = http.createServer(app);
+/*
+ * CRON tasks
+ */
+
+var cron = require('node-cron');
+var UserModel = require("../models/User");
+var ChallengeModel = require("../models/Challenge");
+var GameModel = require("../models/Game");
+cron.schedule('0 0 0 * * *', function() {
+ // Remove some old users, challenges and games every 24h
+ UserModel.cleanUsersDb();
+ ChallengeModel.removeOld();
+ GameModel.cleanGamesDb();
+});
+
/**
* Listen on provided port, on all network interfaces.
*/