Fighter Squadron: The Screamin' Demons over Europe (SDOE) is a Windows-based World War II theme combat flight simulator released in 1999. The game was written by Parsoft Interactive and released by Activision. It was designed for the Windows 95/98 operating system. SDOEs release came on the tail-end of a series of major WWII simulators through 1999, and missed most of the critical Christmas season. Parsoft broke up soon after the release. A version was under development for the Apple Macintosh platform but was cancelled by the Mac porting house during development and the title never made it to the Mac platform.
The simulation player can man all the positions on WWII bombers such as the Boeing B-17 Flying Fortress, Avro Lancaster and Junkers Ju-88. Few combat flight simulators of this time had this feature. In addition, other aircraft could be flown in the simulation including the Lockheed P-38 Lightning, North American P-51 Mustang, Supermarine Spitfire, DeHavilland Mosquito, Hawker Typhoon, Focke-Wulf FW-190 and the Messerschmitt Me-262. The simulation featured a mission editor that players could use to create their own missions. Fan websites created numerous modifications of flight theaters or eras (World War I for example), new aircraft and new missions.
Parsoft's first flight simulator was 1991's Hellcats Over the Pacific, arguably one of the most advanced flight simulators of the era. One of the few common complaints was the fairly basic flight model. The game engine used hard-coded instructions for game maps, mission details and vehicle models and behaviours, making it difficult to modify for new missions. In spite of this, a mission pack was released in 1992. Another issue with the engine was that it was based on integer math, at a time when floating point units were becoming more common. On these platforms, floating point math often ran faster than integer, as the processing was offloaded to a separate unit. At the same time the gaming market was changing; computers were becoming more powerful, screen sizes were growing, and networking was becoming increasingly common.
Parsoft took this opportunity to re-design their game engine. They started with a completely new concept that would allow any in-game element to be loaded from a separate file, and shared around a group of networked computers in what they referred to as the "Virtual Battlefield Environment" (VBE). After writing the engine, they used it to create a game based around the A-10 Thunderbolt II. However, the new game was being released right when the Macintosh platform was moving from the Motorola 680x0 family to the new PowerPC, and it ran poorly on these platforms. A new version for the PowerPC followed, and A-10 Attack! was finally released in 1995.
A-10 fixed almost all of the problems in the original Hellcats engine; networking was built-in from the start, the aerodynamics went from too basic to extremely accurate, a new solid-body physics system was added to control interactions between objects, and the VBE system allowed new game objects to be added to the engine. With A-10's release, Parsoft turned their attention to a mission pack, A-10 Cuba! which was released in 1996.
As had happened between the release of Hellcats and A-10, during the release of A-10 the market had moved once again. In this case the internet was in the process of becoming widely available and taking over from older LAN protocols, graphics cards supporting texture mapping were becoming common, and Apple's market share was imploding. Once again, Parsoft's engine found itself in need of changes in order to keep up with a changing market. A version of VBE tuned for Intel machines, with a new graphics engine, and replacing LAN protocols with TCP/IP would address these concerns. But however good the VBE concept was, its use of shared libraries was a concern when the internal differences between one fighter and the next was limited. A system loading these details from flat files would be idea.
Parsoft started work on just such an engine some time in 1997, originally intending for a Mac and PC release some time in 1998. Returning to the World War II time frame, the new system was originally referred to only as "Dogfight", an indication of its focus. VBE evolved into OpenPlane, which was in turn based on a "parfile", a text file that pointed to other resources for graphics and sounds.