You have to shoot 3 Black Ops 1 DS games. The steps can be done in any order and with a non-pack-a-punched gun.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3383202512
In the spawn area, locate the window to the left of Double Tap. The target is visible outside the window.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3383203476
Purchase the first door for 5000 points. It is on top of the tank.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3383203552
Buy the second and final door for 10,000 points. Stand in the corner between Pack-a-Punch and the nearby window. Look out from this position to spot the last one.

Gg.