Above is a demonstration video of my music toy, January, posted by a random person.
January is a generative music tool. You walk around and look up to lick snowflakes with your tongue. The tool uses a set of rules to make choices about what pitch the next note (or notes) will be. It also gives the player freedom to play various types of chords, and choose when and how notes will be played. There are a bunch of advanced features, which you can explore below. It was originally made with Flixel and Flash/AS3 in 2009 as more of a narrative experience, and later updated in 2013 to be more of a tool/toy.
It has since been revised continuously, and most recently ported to HaxeFlixel by Tim Hely, which allows for native binaries for PC, Mac, etc. Some new features have also been added in the process.