Whereas all of the "Cyber Dragon" Fusions with "Cyber" in their name are LIGHT Attribute, all 3 known "Cyber Dragon" Fusions with "Chimeratech" in their names are DARK Attribute instead.
Similarly, while all "Cyber Dragon" cards include the phrase "Evolution Burst" in their attack names, both "Chimeratech" monsters include "Evolution Result" instead.
Both this card and "Chimeratech Fortress Dragon" originate from the 'Chimaera', a mythical beast who had the head of a lion, goat and snake. More recently, 'chimaera' refers to the idea of combining things that occur naturally, much like both monsters are fused from varying Machine-Type monsters. Their design may also be based on the Hydra or the Orochi.
"Chimeratech Overdragon" is the only "Cyber Dragon" Fusion Monster where all the heads are the same.
In the anime, this card is depicted as having a head for each monster used in the Fusion Summon (e.g. six heads in its first appearance). It could also attack as many times (including direct attacks) as the amount of monsters used to play it; the TCG/OCG counterpart does not apply this to direct attacks.
According to this depiction, the official TCG artwork of Chimeratech has an ATK and DEF of 6*800 or 4,800 since it has 6 heads.
This is the cover card Yu-Gi-Oh! "Tag Force in the pack "wave from the future"
This card is the first Fusion Monster to have a variable number of Fusion Materials.