The vast majority of people with mental retardation have IQ levels of 55 to 69 and are considered mildly retarded. Mildly retarded children often go undiagnosed until they are well into their school years. They are often slower to walk, talk, and feed themselves than most other children.
When Tom Six began creating the Human Centipede sequels, he envisioned a trilogy that works as a movie centipede. Each sequel opens with the ending of the previous film, as the events of that film influence said sequel.
Centipede was ported to Atari's own Atari 2600, Atari 5200, Atari 7800, and Atari 8-bit family. Under the Atarisoft label, the game was sold for the Apple II, Commodore 64, ColecoVision, VIC-20, IBM PC (as a PC booter), Intellivision, and TI-99/4A.