Anti-gravity gun
- The anti-gravity gun is a Decepticon weapon in Generation 1

Originally developed on Cybertron, the anti-gravity gun prooved too unstable to continue using. However, Megatron secretly rebuilt the weapon on Earth, where the continued integrity of the planet is much less of a concern.
The anti-gravity gun is subject to severe and uncontrolable fluctuations in the degree to which it nullifies the effect of gravity. At its highest settings it can cause objects to fly off into space. The version built on Earth is much more powerful.
The unstable energies of the anti-gravity gun could potentially cause a localised rip in the space-time continuium if mishandled.
Fiction
Desert Flight
Backstory
On Cybertron, the Decepticons experimented with anti-gravity gun technology, using it on many Autobot emplacements. The Autobot Smokescreen's home was almost sent floating off into space in one of these attacks. The technology was eventually abandoned after 1) Even the Decepticons found it's unstable nature too dangerous 2) Optimus Prime turned the weapon on them, using its reverse setting to send them plumeting down into Cybertron's lower levels. (The embarassement of the latter probably had more to do with the technology's abandonment than the former did.)
Millions of years later on Earth, Megatron has a secret base constructed to develop the technology again, building a much more powerful weapon. He ordered Dirge to deliberately attract attention so that he could bring the weapon to bear on the Autobots as they approached the base.
Negatron's ultimatum was simple, Optimus Prime woudl deactive himself and give himself to the Decepticons, or he would send every human ont he face of the Earth hurtling off into space. Desert Flight was a multi-path adventure, as such there were many outcomes to this basic conflict. Which Megatron triumped in many of them. In some Megatron triumped, in one he made good his threat to destroy all human life, in many the weapon was destroyed and in one Megatron himsefl was destroyed by the weapon, his parts repelling themselves into pieces.
The anti-gravity gun was apparently developed by Hook, at least on Earth.

