This is a video game written in Python for the 11th Pyweek game programming challenge. It was the highest-scoring individual entry. I've made some slight changes to the game since then, but for the most part it was written completely in one week.
It's a fast-paced action game about collecting butterflies. You can see some gameplay footage on Youtube.
To use the Windows version, download the file, unzip it, and enter the folder. Double-click on the executable file called "lepidopterist".
Just follow the in-game instructions. Controls are the arrow keys left, up, and right, and the space bar. To quit, keep hitting Esc. Press F to switch to fullscreen mode.
The source code and drawings in this game are completely free to use however you want. The sound effects, music, background images, and fonts, however, were not made by me, and are under various licenses, explained in the README. I can tell you that you can modify and redistribute Mortimer the Lepidopterist, if you keep the license information intact, and you cannot sell it or use it for commercial purposes, without replacing a lot of the content. Beyond that, you'll have to check the licenses yourself.