The Further Adventures of A

The oddly-named hero of this story, "A", is bored and wishing something interesting would happen.  When a man emerges from his bathroom mirror, dressed in a spacesuit, and tells him, "I need you to come with me.  You're not safe here, " A is about to get his wish granted on a larger scale than he could have ever dreamed. Originally written is serialized installments and first published in the online magazine SciFantastic, "The Further Adventures of A" is a wild chase through worlds, dimensions, and spaces as the Mirror Man ushers A through a series of doorways and challenges, meeting Leonardo da Vinci, monsters, wizards, aliens, and finally God, all leading up to a world-ending crisis with only one man qualified to save the world: our titular hero, A. With shades of E.
A. Van Vogt and Salvadore Dali, "The Further Adventures of A" is both "cynical" and "original" with one reviewer saying "I was hooked from the first page and couldn't wait to find out what was going on.  There's some great stuff there."