GoldenEye 007 on Nintendo 64 - Agent Mission 7: Cuba - part iv: Cradle

1. Destroy control console
2. Settle the score with Trevelyan

It's on Agent that you get the Cradle cheat code.

a. Destroy control console

Start by grabbing the armour by backing to the right. After following the long path, going down the big slope and down the small staircase, take the door on the left and destroy the 2 gun drones to be safe, then blow up the console. You have 3 minutes to do it once Trevelyan has activated it, which is plenty, because even if you watch the cutscene, he'll only be a few dozen metres ahead of you.

b. Settle the score with Trevelyan

From the console room, exit through the door opposite the entrance one. Trevelyan is at the bottom of the stairs. Try to shoot him in the head without exposing yourself (stay a little to the right of the descent, you should be able to hit him without him seeing you). Before that, you can reopen the entrance door and kill a few enemies to be safe. From there, you'll need to wait for Trevelyan to stop at one of his spots and shoot him again. He stops either at the bottom of a descent (the one you just shot from, or the opposite one, since the level is fairly symmetrical), or in one of the 2 closed rooms (the console room or the other one that contains armour), or at the top of one of the 3 climbs. Overall, once you've hit him the first time, it's better not to follow him and instead go to the other closed room where he should arrive (either there, or at the bottom of the other descent). Personally, I recommend never going down and shooting him from above every time he's below. If he comes into a room, shoot immediately so he leaves again. If he's at the very top, shoot him without going all the way up. Each time, he'll say a line. When it becomes: "Finish the job James, if you can", you can finally go down and head to the middle of the lower area. There, take the small staircase and jump into the hole (take the ladder) in the small room to go settle your score with Alec Trevelyan.

Aim well to land on the small platform and try to dodge his shots or advance toward him while shooting him. He's briefly invincible but dies easily. That's it, you've finished the main story.