This Seeking Tech guide will explain how you can get the “Problem Solved, Series Over” trophy and achievement in the Master Collection version of Metal Gear Solid 3: Snake Eater.
To unlock this, you will need to “create the Ocelot Time Paradox.”
You will first encounter Ocelot near the beginning of the game. After his introductory cut scene, he will be lying on the ground knocked out.
Afterwards, save your game and then kill Ocelot to unlock the trophy and achievement.
You can then reload the save file you created earlier if you are going for a no kill and/or no continue playthrough.