The example (about building an online casino) could be made interactive by using something like Glitch to embed a runnable example. This would basically allow the user to view and edit code/tests files and to run Stryker to see what happens - pretty cool in my opinion 😎
Example here: https://glitch.com/edit/#!/night-lens
(open the embedded console by pressing 'Tools' -> 'Logs', then select the 'Console' tab)