The four years of brutal warfare on the Eastern Front brought the political troops of both sides into front-line fighting. Formed to control civilians rather than fight armed enemies, the Soviet NKVD and the much larger German Waffen SS each committed mass murders in the name of ideology and from simple animal barbarism. Knowing their well-deserved fate if captured, they often fought with suicidal fanaticism.

Sinister Forces brings background articles and scenarios covering these troops and their battles to the Panzer Grenadier game system. It is not playable by itself, but requires Eastern Front to play most of the scenarios, and Afrika Korps or Desert Rats to play all of them. This is a book supplement complete with a full set of die-cut and mounted counters, much like Great War at Sea: Dreadnoughts.