Note that you need to re-assign the Gravity Gun button or clear it completely or the code will add null ammo to the Gravity Gun. Achievement Description Earn gold medals on all Portal challenges. Powerhouse Offense 5 Defeat the chopper in Episode Two without any misses. Long Jump 5 - Jump feet. Counter-Sniper 5 Beat two Portal advanced maps.
Power Trip Win rounds.
Doomsday Milestone Kill an enemy who has damaged the Australium carrier in the last 3 seconds. All the platforms rise again, and the portal is still where you left it. Elevator Action 10 - Survive long enough to get on the parking garage elevator. The Shame of Your Gaming Backlog. When you need to run a long way and have some objects with you for example, a non-explosive barrelif you have the Gravity Gun, use it as cover, and run while facing the enemy to the other side. Zombie-que 5 - Use flares to light 15 zombies on fire. Conservationist 5 Contain the Citadel core.