From their website:
Clash of Titans covers the war between Germany and the Soviet Union from 1941-1945. The Eastern Front, as it was known, spanned over one thousand miles and was the largest theater of war ever seen in human history.
Clash of Titans is the Eastern Front source book which allows you to portray the sharp end of a wide range of actions — from the close combat of partisan raids to long range tank actions upon the wide open steppes.
The book includes unit and equipment lists for the Soviets, Germans, Italians (8th Army), Romanians, Hungarians and Finns — all the major combatants on the Eastern Front from 1941 to 1945, plus rules for cavalry and bicycle troops, parachute landings, amphibious operations, Stuka attacks, city fights, and much more. Clash of Titans allows you to play one-off battles or entire campaigns that can be based around any of the main combatants and campaigns on the Eastern Front. Clash of Titans includes six sample scenarios that span the course of the war – from Barbarossa to Berlin. This is the Eastern Front.