I have written before about how much I enjoy the physical board game Twilight Struggle. This is not really going out on a limb, since it has occupied the #1 spot at BoardGameGeek for a while. But over the last 3 months my son and I became totally addicted. He is at college, but we played online via the terrific Twilight Struggle add-on in the VASSAL gaming engine (all free). Very highly recommended.