The pause menu is drawn last meaning it appears over the top of everything else as this project didn't use any depth buffering. It then pauses everything as all of the animation and movement is scaled using the difference in time between frames meaning if you set it to 0 nothing will move. The buttons were then created by simply drawing sprites over the top and adding rectangle colliders.
The shop screen functions in a similar way to the pause menu as it sets the difference in time to 0. All the elements are again drawn over the top of the Pacman game. This is an ineffective way of doing it but since the game is simple and not resource heavy this isn't an issue. When the user first opens the shop it parses a file and illuminates the correct number of lights. When the user then buys an upgrade the file is updated. The price of each upgrade is also calculated depending on the number of upgrades you have purchased.