use arrow keys for movement
UP_ARROW: FORWARD
DOWN_ARROW: BACKWARD
LEFT_ARROW: ROTATE LEFT
RIGHT_ARROW: RIGHT ARROW
ENTER: START GAME/Resume Game
SPACE BAR: PAUSE GAME
References:
https://permadi.com/1996/05/ray-casting-tutorial-table-of-contents/
https://ncase.me/sight-and-light/
http://archive.gamedev.net/archive/reference/articles/article872.html
https://www.giantbomb.com/ray-casting/3015-1517/