XCom: Enemy Unknown and World of Tanks mostly
XCom i played through on normal mode without much difficulty but then i tried Classic Mode (the next difficulty mode) with Ironman enabled (only one automatic save game.. screw up the game and you can't reload to try again).
I'm honestly a the end of my wit.. i tried over a dozen approaches and sooner or later i am done and on the losing end. The last savegame went pretty well actually.. managed to keep most of the soldiers alive to gain experience and even got to the next equipment level to keep up with the appearance of harder enemies only to lose the entire team in two missions in a row.. now i'm down to one Soldier, basically no money to hire new ones and about 2/3 of the countries on the verge of leaving.
Damn that game is hard.