There are a lot of them to choose from including Pacman and Donkey Kong. Here's how. Click on the Widget button in the the Toolbox. Then, click on the Fun & Games tab. You'll see different categories of fun stuff including text effects and games. To insert what interests you, just click on it, customize by following the instructions and insert!
Popular fun stuff includes shoutboxes, glitter text, and old-fashioned games like Pacman. Below is a Packman example so you see what a game will look like on your site. Enjoy!