would you guys ever want a dlc or a game on its own, containing the origin of the thirteen, including their creation, battle against unicron and the betrayal of megatronus prime (the fallen), where all of them are playable including the mini-con prime and beast prime? with each of them using their own unique weapons (star sabre, requim blaster and etc.)
Hell yeah but only if it was done in a manner similar to RDR's Undead Nightmare. That expansion was a true example of what DLC should be.
I would want it yes, but I don't want it portrayed as fact. I want Transformers origin to be uncertain just like our own religions.
That... doesn't really work here. The canon has it's own religious/historical backing here that the origin game you just said you wanted shares. The Cybertronian race would have one, just one. There is no uncertainty to be had, it is a fact of the canon universe as it has already been accepted.
If you guys haven't or aren't reading the current IDW Comic "More Than Meets the Eye" you should be. The latest Annual dealt exactly with this and stated that there are actually several different theologies for the Transformers.