Guerra de los Huesos
His early writing focused on role-playing games, particularly adventures and support material for Space 1889. His first role playing book was published by Iron Crown Enterprises in 1994, and he has written or contributed to books for Last Unicorn Games, Hero Games, and Steve Jackson Games, including "", "GURPS Mars", "Star Hero", and "GURPS Space". He is one of the founders of Zygote Games, and the co-designer of the game "Bone Wars: The Game of Ruthless Paleontology", based on the Bone Wars of the late 19th century, and "Parasites Unleashed", a game for younger players based on parasitology.