Kaizala

it's not just for enterprise AND it's Free....

Found this at recent Microsoft IGNITE event. If you need do more, need a license which you likely have if you are Office 365 users. Works much like Whatsapp/Wechat. One of the use case is if you have many workers or people in the field that your company needs to communicate with regularly and you don't want to give them an email address (meaning save one email licence, sweet), they need to download this app and you can setup a group to communicate with them. Here is some other use cases:

Source: Microsoft

There is more.There are pre-built actions you can easily use like create a poll in the group and there's even games. Yes, games.