Deemer has had over forty plays produced, dozens of short stories and essays published, and six screenplays optioned. His play Famililly won the 1997 "Crossing Borders" international new play competition. The public television version of his play Christmas at the Juniper Tavern won a regional ACE award. Three of his short stories were selected to the "Roll of Honor" in Best American Short Stories. His book Seven Plays was a finalist for the 2001 Oregon Book Award and his mystery novel Dead Body In A Small Room a finalist for the 2006 ForeWord Magazine Book of the Year award.
Deemer is the former editor of Sweet Reason: a journal of ideas, history and culture and the former managing editor of Oregon Business magazine.
Since the 1980s he has been a pioneer in the new environmental theater form called "hyperdrama," which are plays performed in real spaces with a branching narrative and simultaneous scenes generated by scripts written in hypertext. His seminal essays on the subject, What Is Hypertext? and The New Hyperdrama, have been widely circulated and translated.
In 1994 Deemer created one of the first websites for screenwriters and playwrights, which he maintained until 2001. In 1995 scenes from his hyperdrama "The Bride of Edgefield" were performed live on the Internet at the University of Hawaii's ATHEMOO, each actor at an individual computer; this was one of the first theatrical events in cyberspace. In the summer of 1996, Deemer was "playwright-in-electronic-residence" at the theater company Prisma in Santiago, Chile, developing the one-act hyperdrama, The Last Song of Violeta Parra. Deemer's most ambitious hyperdrama is his expansion of Chekhov's The Seagull into The Seagull Hyperdrama.
Although primarily a playwright through most of his writing career, Deemer began as a short story writer. Recently he has returned to fiction as his major focus, especially in the short novel form. He also has begun collaborating with composer John D. Nugent as a librettist, their first project being the opera Dark Mission.
Deemer has received two Oregon Arts Commission fellowships, one for fiction and one for drama. He won the Oregon Arts Foundation theater award and has been both a distinguished-writer-in-residence and a distinguished-scholar-in-residence at the Catlin Gabel School. Several of his plays have been supported by grants from the Oregon Council for the Humanities. Deemer has taught writing workshops at Fishtrap, the Pacific NW Writers Conference, Moonfish, and elsewhere.
He is the author of an electronic screenwriting tutorial written in hypertext, Screenwright: the craft of screenwriting. His work has been collected in Seven Come Eleven: Stories and Plays, 1969-1999, Seven Plays, Five Screenplays, and Selected Stories. He is the author of several novels, including Sodom, Gomorrah & Jones, Kerouac's Scroll, Baumholder 1961 and Love At Ground Zero.
Presently Deemer teaches screenwriting at Portland State University.