It was included in the Anchorage Reclamation simulation created by VSS at the behest of General Constantine Chase. Its actual deployment in Alaska is dubious, as unimplemented voice clips of VSS technicians in the add-on suggest that their presence is an outright fabrication by General Chase.
Chimera tanks are roughly on par with sentry bots and deathclaws in terms of the durability and combat threat, although they are significantly larger and more imposing in appearance. They are equipped with a unique laser weapon similar to Liberty Prime's eye laser. Chimeras take slightly increased damage when shot in the screws, and noticeably increased damage when shot in the cannon or radar antenna.
The Russian and German military, respectively, did toy with the idea of using screws for treads. The Russian vehicle, named ZIL-29061, was designed to rescue cosmonauts in extreme off-road conditions.
In Greek mythology, the Chimera is a monster with the body of a lion, the heads of a goat and lion, and the tail of a snake. In biology, the name has been used for any organism that appears to have a combination of traits of others. Its name is an obvious reference to how the Chimera tank is a piece of mining equipment equipped with weapons that were not made for it.