In the late 1920s, the Simson company built a handful of prototype pistols for consideration by the German military. Noises had been made about replacing the Luger with something more cost effective, and several companies moved to design options. The Simson pistol was chambered for the 9x19mm Parabellum cartridge (as the military wanted), but was a simple blowback, unlocked action. This allowed it to be cheaper to manufacture, although the military much preferred a locked action. The potential pistol replacement program quickly ended, though, with a decision to allocate funding to development of carbines and submachine guns instead.
Here is one of the 3 known surviving Simson pistols (click to enlarge any of the photos):
Please note that the magazine in these photos is actually a P08 Luger magazine modified to add a locking catch so it will lock into the Simson pistol. However, the magazine is slightly too short to function in the gun, and does not feed properly. I have not found a surviving authentic Simson magazine to photograph.