Simutronics Corporation

Simutronics is an American online games company whose products include GemStone IV and DragonRealms. It was founded in 1987 by David Whatley, with husband and wife Tom & Susan Zelinski. The company is located in St. Louis, Missouri.

The company's flagship product is the text based game, GemStone IV, which went live in November 2003, with predecessor games running back to 1988. GemStone was originally accessed through General Electric's internet service provider GEnie, later becoming accessible through AOL, Prodigy, and CompuServe before Simutronics finally moved all their games to their own domain in 1997.

Simutronics' products GemStone IV, DragonRealms, Modus Operandi, and Alliance of Heroes are text-based multiplayer games built on a proprietary Interactive Fiction Engine (IFE) written in the C programming language. The IFE is responsible for managing the server's memory, interacting with the game's database, and communicating with the clients. It also includes an interpreter for the proprietary GemStone Scripting Language (GSL), a relatively simple language which abstracts away most of the complex details that the IFE handles. Originally, many core game commands (such as those relating to movement and inventory management) were implemented directly by the IFE. Over time, most of those have been migrated to GSL to allow for easier modification.

HeroEngine is a 3D game engine and server technology platform developed specifically for building MMO-style games, based around a system similar to the IFE using the Hero Script Language (HSL). Originally developed for the company's own game Hero's Journey - which never made it to the testing stage - the engine has since been licensed by other companies. Simutronics sold the HeroEngine to Idea Fabrik, Plc. on August 5, 2010.