User Story: Start Game with proper difficulty

[nchapelle]

User Story

As a user I want to be able to choose my difficulty when starting the game

Acceptable Criteria

• [x] index.html has an on click function
• [ ] index.html shows easier and harder modes
• [ ] incorporate a modal to explain the rules

[AmjadShaaban]

I suggest adding a demo location, call it mom's basement in bumblef*** with a little babe drake and we get to explain the rules in it.