This achievement is earned by unlocking 1999 Mode through 1 of 2 methods.
1. You can choose to complete the game on a first play-through on either Easy, Normal, or Hard difficulty.
2. You can input the old school Konami "cheat" code to unlock the mode and play through it right off the bat, if you choose. The following code can be entered from the Main Menu, Up, Up, Down, Down, Left, Right, Left, Right, B, A.
If either method is performed you'll pop this 10G achievement!