Walker designed an award-winning series of board wargames called "Lock 'n Load". The games are squad-level wargames in which a counter can represent a squad, a vehicle or a person such as a sniper or a commanding officer. The first of these games, "Lock 'n Load: Forgotten Heroes: Vietnam" was published by Shrapnel Games in 2003. "Lock 'n Load: ANZAC Attack", an expansion pack was released in 2004. "Lock ’n Load: Band of Heroes", published in 2006 by Matrix Games, is set during World War II. Both "Forgotten Heroes" and "Band of Heroes" were voted best boardgame of the year by readers of "The Wargamer".