Company of Hero's.........There is the original with expansion packs...Very very good, I played, this to death. Now CoH 2 is out..........A lot of new and up dated items, all set on the Russian front. I'm still getting to grips with CoH 2. Have to say I prefer CoH original.

I would highly recommend Company of Hero's.

XCom: Enemy Unknown, Total War Rome 2, Starcraft 2 would all be good places to start...