Transformer Combiner Wars takes place in the future after the war between Autobots and Decepticons has ended and all Transformers have returned to Cybertron. Neither Optimus Prime nor Megatron are around anymore and a new hybrid race of machines has emerged. Ones that combine and transform with any Transformers around them. (Gurren Lagann anyone?). Some of what happened to Prime is described in the first person in the following first 3 minute short.