Here is the full list of all 12 METAL GEAR & METAL GEAR 2: Solid Snake achievements.
Defeat Big Boss in Metal Gear
Complete Boss Survival in Metal Gear
Destroy Metal Gear D
Defeat Gray Fox
Defeat Big Boss in Metal Gear 2
Complete Metal Gear 2
Complete Boss Survival in Metal Gear 2
Start Metal Gear 2
Destroy Metal Gear
Complete Metal Gear
Read all the pages in the Screenplay Book
Start Metal Gear