Since I think I've played as much as I'm going to. In short: Mystic Messenger is a well made and enjoyable phone based dating sim with some aspects I found annoying.
The protagonist stumbles into the chatroom of a group of friends who run a charity, and ends up getting to know them and helping to organise a big party. The game involves joining group chats, answering emails, messages and phonecalls in real time (not real phonecalls etc, it's simulated within the game) as well as traditional Visual Novel scenes.
I wrote up my reactions to most of the routes and some of the DLC as I played.( More detailed review )