He claims that playing violent video games, particularly light gun shooters of the first-person shooter-variety (where the player holds a weapon-like game controller), train children in the use of weapons and, more importantly, harden them emotionally to the task of murder by simulating the killing of hundreds or thousands of opponents in a single typical video game. He has repeatedly used the term "murder simulator" to describe first-person shooter games. His third non-fiction book, On Combat: The Psychology and Physiology of Deadly Conflict in War and in Peace, is an extension of his first, listing coping strategies for dealing with the physiological and psychological effects of violence for people who kill people in their line of work (soldiers and police officers). Criticism University of Nebraska criminal justice professor Samuel Walker characterized Grossman's training as "okay for Green Berets but unacceptable for domestic policing. The best police chiefs in the country don’t want anything to do with this.” Minneapolis Mayor Jacob Frey banned what he termed "fear-based training," a designation that included Grossman's seminars, in 2019. A statewide ban in Minnesota was later signed into law in 2020. Bibliography Non-fiction On Killing: The Psychological Cost of Learning to Kill in War and Society by Lt. Col. Dave Grossman (1995) () Stop Teaching Our Kids to Kill: A Call to Action Against TV, Movie and Video Game Violence (1999) () On Combat: The Psychology and Physiology of Deadly Conflict in War and in Peace by Dave Grossman and Loren W. Christensen (2004) () Warrior Mindset: Mental Toughness Skills for a Nation's Peacekeepers by Dr. Michael Asked, Loren W. Christensen, Dave Grossman (2010) () Assassination Generation: Video Games, Aggression, and the Psychology of Killing by Lt. Col. Dave Grossman, (2016) () Bulletproof Marriage: A 90-Day Devotional by Adam Davis and Lt. Col. Dave Grossman (2019) () On Spiritual Combat: 30 Missions for Victorious Warfare by Adam Davis and Lt. Col. Dave Grossman (2020) () Prayers & Promises for First Responders by Adam Davis and Lt. Col. Dave Grossman (2021) () Fiction The War with Earth (2003) () (with Leo Frankowski) Book two of the series starting with Frankowski's A Boy and his Tank. The Two-Space War (2004) () (with Leo Frankowski) New series. Kren of the Mitchegai (2005) () (with Leo Frankowski) Book three of the series starting with A Boy and his Tank. The Guns of Two-Space (2007) (with Bob Hudson) Book