- Gunpowder Empire: The first book in the series, it involves a pair of siblings stranded during a siege of an outpost of a Roman Empire that never collapsed.
- Curious Notions: The second book in the series is about a teenager and his father who are running an electronics store in San Francisco in a world where Imperial Germany reigns supreme following its victory in the First World War.
- In High Places: Takes place in a world where the Black Death killed four-fifths of Europe's population, and the Moors still occupy Spain and southern France, and the Industrial Revolution never happened.
- The Disunited States of America: This book concerns a pair of teenagers, one from the Crosstime civilization, one a native, who meet in a Virginia where the United States fell apart in the early 1800s due to the Constitutional Convention failing, in a North America torn by war between numerous independent states. The working title for this book was The United States of America.
- The Gladiator: This novel is set in a world dominated by Communism after the Soviet Union won the Cold War in the late 20th century. In Italy, two teenagers chafe under the deadening rule of communism — until they discover the existence of Crosstime Traffic through a strategy gaming shop which is not as it seems.
- The Valley-Westside War: The sixth book in the series, set in Los Angeles a world in which nuclear warfare took place in 1967. Los Angeles and the rest of the United States are split into several tiny republics, kingdoms, city states, and such, we are told a story of when the Kingdom of the Valley invaded the Democracy of Westside.
*Information from Wikipedia
