Eye-opening but probably not "best": the Nullsoft Installer, circa 2002 (https://github.com/kichik/nsis https://github.com/kichik/nsis). Its goal, besides being

Eye-opening but probably not "best": the Nullsoft Installer, circa 2002 (https://github.com/kichik/nsis https://github.com/kichik/nsis). Its goal, besides being an installer, was to produce a small binary. So the source was remarkably pithy, which taught me a lot about being direct and to-the-point rather than aiming for beautiful abstractions or reusability. Similar with Notch's Left4KDead, which implemented a fun zombie game for a Java small-code competition. A mirror of the original source is here (https://github.com/codingcampbell/Left-4k-Dead https://github.com/codingcampbell/Left-4k-Dead). I rewrote it in JavaScript as a Chrome App, in the process refactoring for readability (and sacrificing some of the code's beauty). https://github.com/sowbug/ChromeLeft4kDead https://github.com/sowbug/ChromeLeft4kDead