Commandos meets Hitman. Just like Commandos it's almost a puzzle game, working out which guards to take out in which order. Great game if you have the patience - just remember to enable the map overlay which shows enemy fields of view.

There are a couple of must-have mods floating around the internet. One restores cut historical symbols, the other replaces the bad American voice acting with the original Russian, with English subtitles. Atmosphere is improved ten-fold.