Baba Yaga: The Secret War

Designers blog post:

Baba Yaga is an extremely flexible – and rather fast-playing and lethal – universal RPG. Although the default setting is WWII, with the characters as members of partisan resistance movements in the Ukraine which operate out of hidden magical enclaves (and thus have access to small magical abilities to give them a chance against the far better supplied and numerically-superior german forces), the game works perfectly well for a straight no-magic military campaign, for superhero adventures, and for space opera, and for various other settings.