Ok, heres my Heroes of Cybertron version of Megatron.

Hes a mix of G1, and My original HOC design, and maybe with Bay's detailing.

He's a Stationary cybertonian turrent gun in alt form, because he doesn't need a mode for transport,he can fly, nor would he hide. So the only real reason he would want to turn into , anything, is for pure devastation. No better way to channel that power than to focus one full blast as a giant turret cannon. Unlike G1 his arm cannon is grey, the same color he is, but after years of destroying autobots, it has developed its blackish color from laser burns . The canon is harnessed to his back and retracts to his back when not in use, then moves around his body and connects to his forearm for firing. The etched marks represent the amount of autobots he's killed on earth. After a kill, he places his left pointer finger into the hot barrel of his cannon, waits for it to glow orange then burns his kill mark on to the surface.

NOW THIS... THIS IS FUCKIN MEGATRON.