Bad Apple!!

"Bad Apple!!" is the seventh track in the soundtrack of the 1998 bullet hell video game "Lotus Land Story", the fourth entry in the "Touhou Project" series created by Team Shanghai Alice. The instrumental theme was originally designed to be played during the third stage of the game, as chiptune on the Japanese NEC PC-9800 computer platform, at 161 beats per minute using a frequency modulation synthesis chip.
It is notable for leading to a much later remix by and singer Nomico and following the remix a subsequent accompanying black-and-white shadow puppet-video. In the 2010s, the version sung by Nomico and the black-and-white video sequence were ported to several second-generation video game consoles and graphing calculators, for retrocomputing and demoscene competitions, becoming a graphical equivalent to the "Hello, World!" programs of older computer systems in the demoscene communities.
Naming.
The name likely derives from the proverb that "one bad apple spoils the bunch".
Pop song.
In 2007, a longer cover version featuring the Japanese singer Nomico was released in the album "Lovelight" by the artists group Alstroemeria Records, lead by . It shared little similarity with the original soundtrack, borrowing only a little of melody samples, but nonetheless it was notable as being the only vocal song in the album, and for its lyrics dealing with depression and apathy.
Music video.
In August 2008, a user in Nico Nico Douga uploaded a video of a crude storyboard based on the remixed music, asking for anyone to animate it. Several animation videos started appearing, with relatively few successes. 
Between October 2008 and October 2009, a collaborative group led by Anira (あにら) created a shadow-art (black and white) animation video based on the storyboard, which was released on Nico Nico on 27 October 2009.
10th Anniversary.
In 2017, the Alstroemeria Records group released a "10th Anniversary Bad Apple!!" album consisting entirely of "Bad Apple" remixes.
Demoscene.
The shadow puppet video has been used in the demoscene as the basis of many ports for older computer platforms, presumed to be incapable of playing back full motion video.