Mission 16: Escape from the Southern Fields

Superstructure Stand-off is the sixteenth mission of Halo: Spartan Assault. Completing the level using only the Brute Shot, melee, or grenades unlocks the Brute Force achievement.

Introduction
Across Draetheus-V, the effects of the activation of the moon's Forerunner structure were being felt. Enormous slabs of rock were slowly floating away from the planet's surface and both UNSC and Covenant troops were scrambling to get to safety

Spartan Palmer needed to get every last survivor off Draetheus-V as soon as possible. But as the planet started to disintegrate, a panic rippled through every infantry unit on the field. A coordinated retreat would be impossible. Fighting her way through hordes of fleeing Covenant in a rapidly disintegrating base, she managed to secure jetpacks to get her to safer ground.

Destroy the main gate
Spartan Sarah Palmer has three minutes and thirty-three seconds to escape the destroyed base before it collapses. The Spartan and a singe UNSC Marine stand outside the base's walls and are attacked by three Unggoy Minors. After quickly killing the Grunts, Palmer and the Marine use grenades to blow up a wall to access the base. In the background, the planet's plates begin to shift or lift up into the air. As the two humans manage to destroy the wall, they are attacked by a Jiralhanae Jumper who lands behind them. After killing the Brute, Spartan Palmer and the Marine continue through the base.

Destroy the armory door
As the Spartan and Marine progress through the collapsing base, they encounter several fleeing Unggoy that are trying to escape the base's destruction. They encounter a second Marine and the group fights off the Covenant forces. A Brute Jumper lands nearby. After killing all the Covenant forces in the area, they begin to destroy the doors to the armory with explosives. While doing so, several Unggoy and Sangheili Minors attack the group. However, Spartan Palmer and the Marines succeed in holding off the Covenant forces and destroying the armory door.

Enter the armory to get a jetpack
Large amounts of Sangheili and Unggoy forces continue to attack Palmer and the Marines. Several Jiralhanae Jumpers land nearby and attack the Spartan. Eventually, Palmer kills most of the Covenant forces and enters the armory. While inside, a Jiralhanae Jumper begins to make his way over to Palmer. However, Palmer exits the armory wearing a jetpack and flies away from the base. As the Jiralhanae watches, he is crushed by falling debris.

Gameplay

 * Most people decide to stall or hang around until the last second before the countdown ends. Normally it's performed by players who aimed for the high score on this mission.
 * Spartan Laser can do both objectives at the same time since it can also hit the Armory door while also hitting the main gate at the same time due to piercing capabilities that have same amount of damage.