MGS1... Meryl got tortured to death by Ocelot.
because I couldn't endure the "torture scene".
It was just so well put together as Snaked trudged off into the Alaskan wilderness in the dawn sunrise, with his new nerdy friend Otacon, who I identified a lot with personally.
But... in many ways I was disappointed that future MGS games were based on the "good" ending where Meryl survives. Because the bad ending really had meaning, Snake had failed, ocelot had made a vendetta and gotten away likely by making a deal with the US Authorities.
It would have made for a much better sequel, with Snake on a personal mission to fight Ocelot. Not ocelot as possessed by Liquid, nor Ocelot who "thinks" he is Liquid but Ocelot himself as himself. Ocelot's own motivations were interesting enough.
Snake and Otacon, David and Hal, they were kindred spirits, both had separately found love on Shadow Moses though had it cruelly taken from them... only Snake had killed Sniper Wolf... and now he was going to kill Ocelot for killing Meryl. That would have made for interesting future games to say the least. And Colonel Campbell would have a reason to come along as well, it was his daughter who had been killed, it was a personal revenge mission... or at least that's how it would start.
MGS3 gave ocelot an intriguing back story which was thrown out the window with the ridiculous possession by Liquid that made no damn sense. Kojima should have stuck with the original idea of giving ocelot a mechanical hand and never tried to re-introduce Liquid Snake.