Pygame is a set of modules designed to help you write Python games by providing you with extra functionalities and libraries. It's free, supports Python 3.2 and up, runs on just about every operating system and platforms, and has over a million downloads, so it's very widely used.
Pygame is super speedy because it uses optimized C for core functions (C can be up to 10 or 20 times faster than Python). The library also provides speedy and attentive support -- expect them to be very responsive if you find a bug or run into any issues with the code. Thousands of games have been made using Pygame, including this arcade style game where the objective is to shoot as many asteroids as you can and pick up stranded astronauts to return to the space station.
Not only is it fun to make games using Pygame (the creators say that "silliness is included"), but it's also loads of fun to play the games created using the library. If you're a game maker who's been been looking for modules and libraries that make the process of creating Python games quicker and more efficient, Pygame might be the right tool for you. If you need help getting started, be sure to check out the tutorials page.