Title explains enough.

(Completed) A cowboy finds himself thrown into a new world, one with powers and monsters unlike any he's seen before. The monsters he meets are more dangerous than any he's met before, and the powers he discovers exceed that of a human's. With his trusted horse and guns on his hip, he wants to make it back home, alive. The only question is how he will, or rather, if he will? Part I of The Gunslinger Series Disclaimer: Language and Some Dark Scenes

Come on. It's a Ruby story. You know what's going on. As always, a massive thank you to @blake21takeshi for the incredible drawings. This story wouldn't be the same without him.