Call of Duty: World at War

If you're not tackling this one solo, all you need is two people. Before the end of round 4 you should be able to make it to the power switch/Random Box. Leave a straggling zombie/couple of slow zombies and open up as much as you can to progress towards each teleporter.

THEN, when you're ready to link, one of you stands in the teleporter and the other (or someone else if you have 3 or 4) runs back to the mainframe when you've got your straggling/slow zombie. THE PERSON WHO BEGINS THE COUNTDOWN DOES NOT HAVE TO BE THE ONE TO RUN BACK! Teleporter-person pushes X, mainframe-person pushes X when prompted.

-Continue the method of acquiring enough points with a straggling/slow zombie.

-Also, my friend and I got this DURING round 7 so it's really before round 7 is over.

-Everyone in the party should get the achievement no matter who's doing what.

I have found that is easiest to do this with 3 people...

by about round 3 each of you should have 2-3k points (if you have trouble getting this manyt points here's a tip: dont buy weapons, in the first round you can pistol a zombie 5 times then knife for about 180 per zombie, i think it might be just 150 but its still more than you would get, during round 2 you can shoot them 6 times and in round 3 you can use an entire clip, if you start to get overrun, buy the gehwer it has lots of ammo and is easier to headshot with than the Kar)

go to the random box through the side with the gehwer

once you randomize at least one person should have an automatic, such as a PPsH or Tomhpson or Type 100

after round four the person with the automatic heads towards the mainframe, but first gets the teleporter on the side you went through

he then gets to the main frame and links it, he will hold out here until all teleporters are linked

the other two will hang back at the random box until the first teleporter is linked, then they will open the door behind them and link that teleporter

once the second teleporter is linked they will head to the last one (this should be about the beginning of round five or the end of round four)

if you have enough points, you should teleport to the mainframe so that all of you can make your way to your hold out location together

if you dont have enough to teleport, hold out until the end of the round, then everybody heads to your hold out location alone

if you prefer to play with 4 people, move in pairs, and wait till the after the fourth round to start, so that you have enough points to finish

also, i suggest using the area of the second teleporter linked on my list,

you can head upstairs, only having to cover a window and the long staircase... also there is a small glitch here that if you head to the spot where the random box can be, dogs will move slightly slower when they are on the staircase

This is very easy to do solo. I had them all linked by the end of round round 4! Thought that was with a max ammo bonus in round 1 and a 2x bonus in round 2, so it'd probably take a few extra rounds without luck like that.

Here's a general rundown:

Round 1: Knife every enemy as soon as you see them behind a barricade. Open the first door on the right of the mainframe (with your back to the pack-a-punch).
Round 2-4: Shoot enemies five times before knifing them. When ammo runs out, keep knifing them. You should have the second door behind the one you just opened by now. Buy the Thompson as soon as you can, and open the barricade on the stairs by that gun. Jump down and turn on the power. You can now link the upstairs teleporter, behind the staircase barricade you opened earlier.
Round 5-7: Open the door behind the power switch and activate that teleporter. Then go back the mainframe and open the door opposite the one you first opened (left with your back to the pack-a-punch), then open the first door behind that and once inside, go around the chainlink fence on your left (turning left twice), open the door and link up the teleporter. For some reason, the first door in this sequence was closed again when I did it. If that happens to you and you don't have 750 points to open it again, you do have enough time to run around the entire mainframe courtyard and just barely make it to the teleporter.

Of course, remember to leave a slow zombie or create a crawler by tossing a grenade at the end of rounds 3-7 so you have ample time to activate teleporters or open barricades, if you have the money to do so. Also, always go for headshots to maximize your point gain. Never grab nukes if you don't need to (as they only give 400 points compared to potential thousands in headshots).

One last thing: if you somehow forget which ones you've linked, there's a handy map by the upstairs teleporter. Green light means activated teleporter, obviously.

Der Electrician! - 25G
Make sure you get them before round 7.
Best won with freinds since it is harder in round 5 and above to get to the mainframe in time.
A good way to do this is to make sure you have enough points for the doors between you all and then leave one zombie as a crawler or otherwise and then link all the pads.
you link pads by getting in them and pressing X to link it to the main frame, the timer will then come up and give you a countdown to get to the mainframe, beware if you run out of time you will have to repeat the process for that teleporter pad(going back to it and pressing X again)
(This will also unlock the Pack-A-Punch for use which you will need 5000 points for)