Change effective on 06 June 2017
Play 1.x is no longer supported on Heroku (deprecation notice). Your Play 1.x apps WILL continue to work on Heroku, but the buildpack will:
You can continue using the Play buildpack by manually setting it with the command:
$ heroku buildpacks:set https://github.com/heroku/heroku-buildpack-play
Support for Play 2.x will continue to be provided by the Scala buildpack.
For more information on using Scala and Play 2.x please see the Dev Center guide for Deploying Scala Apps on Heroku.