Dave Allsop developed the role-playing game SLA Industries (1993); the Scottish company Nightfall Games was founded solely to publish the game.:280 Wizards of the Coast later bought SLA Industries, but then returned it to Nightfall, who licensed it to Hogshead Publishing; in 2002, Hogshead closed down and thus SLA Industries returned to Allsop.:427 Allsop was by then the flatmate of Angus Abranson, and they decided to form a new role-playing company in 2003 called Cubicle 7 Entertainment.:427 Allsop started work on a new release of SLA Industries, but in the Fall of 2004 Allsop decided to pull out of Cubicle 7 to pursue other opportunities.:427 In 2005, Allsop, with Adrian Bott, produced The Book of Unremitting Horror, a book of monsters for the d20 System, published by Pelgrane Press.:384 Allsop returned to Cubicle 7 in 2007 as the SLA Industries line editor, which started releasing new books again in 2011.:427
His Dungeons & Dragons work includes interior art for Eberron Campaign Setting (2004), Monster Manual III (2004), Expedition to Castle Ravenloft (2006), Cityscape (2006), Fiendish Codex II: Tyrants of the Nine Hells (2006), Fantastic Locations: City of Peril (2007), Monster Manual V (2007), An Adventurer's Guide to Eberron (2008), the fourth edition Monster Manual (2008), the fourth edition Manual of the Planes (2008), Demon Queen's Enclave (2008), Draconomicon: Metallic Dragons (2009), and Martial Power II (2010).
Allsop is the concept artist for One Thumb Mobile, for their game Celtic Heroes.
- Shannon Appelcline (2011). Designers & Dragons. Mongoose Publishing. ISBN 978-1-907702-58-7.