His works include:
- The Lost Regiment series
- The Ice Prophet series
- The Star Voyager series
- The Gettysburg Trilogy (co-authored with Newt Gingrich)
- The majority of the Wing Commander Expanded Universe novels
- A currently unnamed series focusing on the American Revolution, also co-written with Newt Gingrich. Current titles include To Try Men's Souls and Valley Forge.
- One Second Later, which is about the aftermath of the US being struck by a nuclear EMP, and its sequel One Year Later.
- Day of Wrath, about ISIL cells attacking several elementary schools across the US simultaneously.
Works with their own trope pages include:
Other works contain examples of:
- After the End: One Second After is a Cozy Catastrophe that begins with an EMP attack on the US and tells what happens in the following year.
- Alternate History:
- In the Gettysburg Trilogy, the Battle of Gettysburg went differently than in reality, with knock-on effects for the rest of the Civil War.
- In 1945, Germany stays out of the War in the Pacific and the US stays out of the War in Europe.
- China Takes Over the World: In One Second After, China is one of the few nations to survive the EMP attack comparatively unscathed. The Chinese take over the Pacific Coast at the end of the novel, and are actually welcomed as heroes because they bring much needed food and medical supplies. Mexico is threatened by the Chinese military buildup in California, leading to rivalry.
- Divided States of America: By the end of One Second After, the US has split into several parts. China has taken over the West Coast, Mexico has grabbed a large chunk of the South West, the US Government controls the East Coast and the rest of the country is more or less up for grabs and in chaos.
- Dyson Sphere: The Gamester Wars series has a Dyson Sphere setting that's still being built—the Precursors' ancient robots have been at it for millions of years and it's still only half-complete, because of its size. There's also a Ring World Planet and other stellar-scale objects in the same universe.