There are four challenges in Black Ops 2 Origins that you are required to complete in one run in order to unlock Overachiever achievement. These challenges are:
- Headshot 115 Zombies (Normal)
- Activating 6 Generators
- Spending 30,000 Points
- Filling 4 Chests to Capacity
After finishing a challenge, go to the Stone Box where all challenges are named, to claim a reward. You can get Pack-a-Punched Gun, perk, ammo, and explosive melee punches.
Getting headshots on 115 normal zombies is simple and so is spending 30,000 Points. Although I would recommend an Assault Rifle for taking the headshots.
As for activating the generators, you can refer to my generators locations guide for more assistance on this particular challenge. Although you don’t have to activate them all at the same time for this achievement.
The chests that you are required to fill up are located at the following locations:
- While coming out of the Workshop, to the left hand side of the Excavation Site
- Near Generator #5
- Alfresco the church, near the cemetery
- Next to Generator #4 and MP40
To fill up these chests, you have to kill the zombies around them. Since completing this challenge is difficult, I would rede you to use some decent guns, a lot of perks, and a Juggernaut.
There are not only zombies near these chests, but the Giants and Panzer Soldats can also come by; making this even more difficult. Note that if a Giant treads on a chest, it will close and you will have to start all over again.
As for the Panzer Soldats, try to evade their claws and shoot them in the face for an instant kill. Use Ray Gun or MKII and easy difficulty to get this done!
Once you complete all the challenges, your achievement will unlock.