Prompt: Write a short story about a man who discovers a magical portal

Bill had always been fascinated by mysterious portals. He found they always seemed to lead to some amazing place. So when he found a portal that led to an alternate world, he thought he had hit the jackpot.

As he stepped through the portal, everything around him changed. The air became chilly and the sky was dark. Bill struggled to adjust to his new surroundings, but he quickly realized that he was in the middle of a fight.