Bob Corderey offers Red Flags and Iron Crosses, a set of free wargames rules for playing World War II games in 20mm. The rules focus on small actions between Soviet and German forces.
World War Two
East Front Sniper Game
In East Front Sniper, each player acts as a World War II Soviet Sniper, competing to rack up the most kills.
Warhammer World War 2
Warhammer has been adapted to every period I can think of. Here’s a version called Warhammer Panzer Battles