This app was mentioned in 4 comments, with an average of 6.00 upvotes
Links for your convenience:
Google Playstore
App Store
Play store link. I got redirected around a lot when I went OPs route.
https://play.google.com/store/apps/details?id=com.bethsoft.falloutchat
https://play.google.com/store/apps/details?id=com.bethsoft.falloutchat&hl=en
its on android too https://play.google.com/store/apps/details?id=com.bethsoft.falloutchat&hl=en