You can create an app in Heroku with Crystal's buildpack by running the following command:
$ heroku create myapp --buildpack https://github.com/zamith/heroku-buildpack-crystal.git
In order for the buildpack to work properly you should have a Projectfile
file, as it is how it will detect that your app is a Crystal app.
To learn more about using custom buildpacks in Heroku, read theirs docs.