So here it is, just an idea:
In an undetermined time in the future Transformers have become nearly extinct. To many races the Transformers are warmongers, so they´re hated among the stars. This situation, along with the lack of energy sources, forces them to create smaller bodys for themselfs, capable of mimicking the appearance of organic beings.
All that remains are the hatchlings (seen in ROTF and DOTM), with every other Autobot and Decepticon long gone. To some Megatron is Cybertron´s greatest hero, the one who kept them alive and did everything in his power to save the planet, they call themselfs Predacons (
). To others, Megatron was a mad man and Optimus is their true savior, these are the Maximals.
OK, so a Predacon named Megatron uses a time machine to go back to prehistoric Earth and obtain the energy of the Allspark, so he can become ruler of the known universe. What he doesn´t now is that a group of Maximals infiltrated his organization and traveled along with him.
They arrive shortly after the arrival of the Allspark (10.000 B.C.) and get beast modes, some from living animals, others from fossilized creatures. The Energy Harvester built by the Primes is uselesss without the Matrix, but they use it as a base of operations. Soon they head to retrieve the Allspark. Optimus Primal, disguised as Onix Primal, fears that the tampering of the Allspark may atract the attention of the Cybertronians from that time period, so he and his men unveil their cover and battle the Predacons, traping them inside the Harvester so they can´t get to the future site of the Hoover Dam.
Getting there, the Maximals find that the Allspark isn´t there. The Predacons, better equiped for the mission, scape and find the energy signal from the cube in Antartica, close to the place where Megatron will crash some milennia later. Unable to get there in time the Maximals can only watch the energy outburst caused be the Predacons. The entire planet starts to shake while a power-mad Megatron declares his supremacy over all other sentient beings.
Believing himself to be allmighty, Megatron decides to travel to Cybertron and conquer it, thus changing history and destroying all his enemies before they even exist. As The Cube elevates to the atmosphere, Primal confronts Megatron while the Maximals do everything they can to destroy the Predacons. In an epic final battle on top of the flying Allspark, Megatron savagely beats Optimus, forcing him to open up his spark chamber and merge it with The Cube. The resultant explosion, though not as powerfull as spected, is strong enough to stop the movement of The Cube in midair. Earth´s gravity pulls back the artifact making it crash in what will become Nevada (
With the Predacons scattered across the globe and Primal´s body missing, the surviving Maximals declare, like his Autobots ancestors did or will do, Earth as their new home.
To be continued?