you mean the plot? Well, uh... After the Doomguy triumphantly saved Earth, he decided to keep the teleport to the monsters' dimension for himself. But one day, as he was fixing his BFG, he went to the toilet and returned to see his new pet bunny "accidentally" knocking the table down, teleporting the BFG to the aliens' dimension. "Dammit" -- says the Doomguy -- "looks like I won't be bored this weekend". And with these words, he grabs his trusty pistol, leaves a 2-week supply of food to his bunny and jumps into new adventures. Yeah, I know what you are thinking about. PS. No Winnie Pooh here.
Credits:
the guy who created the official tutorials for Doom Builder 2.