|The following is based on Van Buren and is not canon.|
Maniac was never mentioned in the text of the Reservation design document; however a pre-War photograph of Dr. Clark and Dr. Sebastian included in the document cites MANIAC as one of their finest colleagues.
Maniac has not appeared nor is it mentioned in any published game. It may have appeared in Van Buren, the canceled Fallout 3 by Black Isle Studios, but it is not certain as it is only included in a sample picture to help demonstrate two of the characters at the location. It is not certain if it will appear in any future Fallout game.
Behind the scenes
Several real life computers have been called MANIAC (an acronym for Mathematical Analyzer, Numerical Integrator, and Computer or Mathematical Analyzer, Numerator, Integrator, and Computer), two of these were built for the Los Alamos Nuclear Testing Facility.