A great ES6 + Phaser 3 Bootstrap Template and a platform game example to learn from as well!
nkholski has released an excellent package for anyone wanting to get started with Phaser 3. It consists of a Bootstrap project, combining Phaser 3 with ES6 and Webpack. It's worth downloading for this in itself.
However it also includes a full platform game project that explores the Phaser 3 API. You may well recognise it from the screen shots! There's a live demo available and you can go through the platformer source code to learn how how it uses Phaser 3 and how things are different now.
An invaluable resource for those who'd like a quick v3 bootstrap, or a platform game example, or both!