All According to Plan...

All According to Plan... is an achievement in Halo: Combat Evolved Anniversary that is awarded for killing all the enemies in the first encounter in the level The Truth and Reconciliation without being detected. It is worth 25 Gamerscore points. It is represented by an M6D target reticule surrounded by a pink star, which in turn is surrounded by a purple octagon.

To get this achievenment, it's a good idea to snipe from behind the rocks patiently, taking cover whenever enemies start to run blindly towards the player. When no more enemies can be seen, walking along the ledge would usually reveal a sleeping Grunt that may be on the lower level.

The Achievement is worth 25 Gamerpoints.

Tips

 * In the beginning area, when hiding behind the rock formation with the opening, do not "lean" against the rock as enemies are almost guaranteed to notice you after firing a shot. Instead, try to stand several feet back away from the formation in order to avoid being detected by enemy AI.
 * This achievement can be unlocked on Easy which can be used to the advantage of the player(s) as all of the enemies will die with single sniper shots.
 * To get a clearer view of all enemies in the first encounter, it is recommended to use "Classic" mode which will reveal hidden solid surfaces and remove foliage that may obscure enemies.