This is a story-related achievement and cannot be missed while playing the Gaea campaign. In the endgame you will be in a custom Manta chasing Shin's shielded Manta. Your Manta heals itself slowly when it is not taking damage, but you will still need to avoid running into the ground or trees. Most of the chase is repetitive loops across the same areas, so you may find it advantageous to shoot turrets early. Most of the aircraft and land units you can safely ignore, although with the super gatling your Manta is equipped with, everything other than Shin is a one-shot kill. The game autosaves at several places along the chase, and you can just focus on avoiding the terrain and shooting Shin. There is one more achievement that is broken after this, so if you don't care to see the ending you can skip the footchase that starts up after shooting Shin down.