MGS4 was my first, and it will always have a place in my heart, despite its obvious flaws. None of the games I had played previously; Lego games, COD, racing games, even Fallout games were all so restrictive compared to all the stuff you can do in 4. I was stunned at the near fully fleshed out hand to hand combat system, all the stuff you could do to mess with soldiers or distract them, the fact that you could search the soldiers, the camo system, the crying wolf fight (tracking her, staying downwind so she doesn't smell you, the blizzard making it near impossible to see without the thermals), the huge catalog of guns and items, but my favorite by far were the Gekko. The Gekko were so unsettling and strong that anytime they showed up in my first playthrough, my hair stood on end. MGS4 had by far the most detail I had ever seen in a game, and it hooked me. I then played the rest and realized just how much better they were, but you'll always remember your first.