How to insert Phaser game into Big Title section?

So I have Zerif lite theme, where I would like to insert external Phaser game file to appear in Big Title section. But Big Title section does not allow to set widgets on it.

So,

1. in what folder I put my Phaser folders and files? Codes are in own folder and separated to own files. e.g. preload.js, level1.js, level2.js etc. and all files are linked together in their code. Graphics and levels are in own assets folder.
2. How do I insert main.js to big-title.php so the game can be played?