Mercenaries, Spies & Private Eyes RPG was first published in 1983 by Flying Buffalo Inc. MSPE (as it came to be known) allowed players to run rpg adventures from the 1800's all the way to the modern era, ranging from Victorian steampunk, and crime noir, to super spy thrilllers in the cold war. Michael Stackpole wrote the MSPE role playing game, using the Tunnels & Trolls framework as a jumping off point.

In 1986, Flying Buffalo took a hit from an unrelated disaster, and sold the rights of MSPE to Sleuth Publications. They came out with an edition that had a black & white cover, and they left out a few things that Buffalo had included, and inserted a few new things that weren't in the Buffalo edition.