As a project, Flywrench also has plenty of history. A prototype was originally released in 2007—and its flappy-line protagonist was a bonus character in Super Meat Boy. Flywrench was also the star of a Kickstarter (opens in new tab), funded way back in 2009.
Here's what it looks like:
What's going on there, then? Your Flywrench has a few different states—static, spinning and flapping—and a different colour for each. To pass the coloured gate, you need to be performing its associated action. And therein, the challenge. In addition to its 170+ levels, Flywrench also boasts a level editor. That's a lot of levels.