I am going to document my method that I used for solo as it includes detail not included in the other guides. It includes an exploit that makes life easier. Read on to find out. This should work for most of the map pack 3 achievements but is not recommended for 40 Knives as its too risky or Perkaholics Anonymous! as we will be buying perks to survive. You may get Der Electrician depending on luck or from changing my steps around a bit to suit.
Pictures and Videos can be quite useful so I am planning to add both but I wanted to get the process down whilst it is fresh in my head.
This does require some skill, luck and good map knowledge. But I will give you my steps that hopefully will make things a bit easier.
I am also going to break this down into simple steps so if you are experienced sorry, just pick out the bits you need - you may want to drop down to the exploit section. If its too long for you to read, sorry but I couldn't streamline it much more.
The biggest challenge with zombies is things get fairly frantic and you need to try to maintain composure.
Buy yourself time
In Solo there are two ways to do this
1) Pause the game by hitting the start button. This just gives you thinking time. Plan your next move.
2) Create a crawler. You do this by hitting RB to throw a grenade and hopefully blow the legs off a zombie. This gives you time to do things on the map such as get weapons and perks and repair windows. This is a crucial part of the game.
Power Ups From Zombie drops
Instakill - One hit kills with anything. A knife hit or a single bullet. Always useful and makes later rounds easy. Just remember you can't make a crawler with instakill active so if you only have a few zombies left you may ignore it or if its active run around with the last few following you until its run out.
Bomb - wipes out everything on the map. Early on this finishes the round, later on (15+ I think) it clears a lot of the round but there may be more zombies spawn. Adds 400 points if there is at least one zombie. Most of the time you will want to AVOID this as it reduces your points. Use it if you are in real trouble or if there is only one zombie left as it will provide more points then killing the last zombie.
Max Ammo - Refills your ammo supply for both guns and monkey bombs if you have them. Always try to reload your guns first then pick it up. Always good.
Carpenter - Rebuilds walls, which slows down the zombie onslaught a bit in later rounds. Adds 200 points. No harm in getting this but don't risk yourself to pick it up.
2X - Another great drop. Watch your points fly up.
Window Repair = 10 points per board (This will stop working during the round usually after you pick up around 200 points)
Non-fatal bullet or knife hit = 10 points
Fatal bullet body shot = 50 points
Fatal bullet head shot = 100 points
Knife kill = 130 points
Getting a good start and maximising your points is important. Later on the points are easier to get and its more about survival.
The early rounds are really important to maximise your score. Zombies can take 5 pistol shots to the BODY and then knife them giving you 10x5 + 130 = 180 points per kill. Repair some windows to add some extra points.
Round 2 zombies can take 8 shots then a knife. Round 2 usually provides a Power Up drop. Instakill means stop shooting and knife everything. Max ammo means you can keep using your pistol. 2x means carry on as discussed. Bomb, use if there is one zombie left. If you run out of ammo grab a Kar98K from the back of the starting area for 200. With this gun you can gut shot them once and then knife them for 140 points.
Round 3 if you got a max ammo keep firing your pistol at them. You can get 10-12 shots in them before knifing them. It will start to get crowded now so before you get overwhelmed open the two doors (750 each) through to the Thompson room. You should either be close to or have enough for a Thompson so sell your pistol if its out of ammo and replace with the Thompson. Towards the end of this round you should also have 1,000 to clear the barricade at the top of the stairs. Turn left and you can drop down into the mystery box/power area. If you move to the back of this area near the power switch you will be in a good spot to hold up. DO NOT open the 1250 door behind you yet. Turn on the power now. Stop knifing now unless you get an instakill and its safe and aim for headshots to get the best points. Depending on how well you have done in accumulating points you may be able to squeeze enough money to hit the mystery box.
** From now on you should always attempt to make a crawler at the end of every round **
By turning on the power you will be able to make your way back to the starting location and repair windows to help up the points.
If you are still short of points for the mystery box start round 4. The Thompson should be sufficient to hold this area. If you stand near the power switch you should get two lines of zombies running towards you allowing you to head shot them. If you start to get swarmed you can toss a grenade to try and slow them down. Getting a crawler would be great. The other thing to do is run a circuit.
Try and weave your way through them I usually run through the door on the right and then head past the speed cola back towards the Thompson room. Once you are at speed cola you don't need to sprint and can periodically turn and shoot to reduce the numbers or throw a grenade to get a crawler. Head into the Thompson room, turn and shoot again, up the stairs drop down and you are back at the power area with less zombies and back in control. Later on your circuit may have changed but the principle is the same. When safe turn and fire back at the horde to thin their numbers down before you get to your camping spot.
At this point the rounds are less important and its more about achieving certain goals to build your survival chances so I will break the guide down by goal which you will proceed with as you can afford it. But before I do about round 5 you will encounter dogs which deserve a mention.
You may get a dog round in round 5 or 6. You can tell cause the fog comes. Your Thompson can handle them easy and your location by the power box is fine. They will appear as a ball of lightning. Pick them off as soon as you can. Mostly they will come one by one and you can side step them if they get too close. The round finishes with the last dog dropping a Max Ammo.
Goal 1 - A good gun from the mystery box - Cost 950 per roll.
At this point you have a Thompson which is a pretty decent weapon. You will switch to your other weapon, probably the Kar98K or starting pistol and swap it out for the mystery box.
Ideally you will get either the PPSh-41, MG42 or the Browning M1919. If you get one of these awesome. You are in business! The PPsh-41 is the best gun in my opinion as it has the firepower and magazine size but is also lighter than the MG42 and Browning which slow down your running speed. Go to the Juggernog section.
If you get the Wunderwaffe DG-2, Ray Gun, STG-44, MP40, FG42 or Type 100 you can proceed but we are going to want to roll the box later and replace this weapon(if you have the Wunderwaffe DG-2 or Ray Gun you would want to replace your Thompson) with one of the three mentioned above later. Go to the Juggernog section.
Monkey Bombs are a good roll but you are going to want to stay and get another roll of the box for a better second weapon You can use a monkey bomb (Press LB) if it gets busy. Remember to shoot them while they are crowding around the monkey bomb.
Anything else is probably better than the Kar98K or Pistol but not really good enough to proceed so stay and have another roll. If you get two or three shit weapons from the box contemplate restarting.
Now with the Thompson and a good second weapon we need to save 2,500 to get Juggernog. Camp in the Power area as described above until you have the points. Remember to get a crawler, repair the windows and try and get 2,500. Once you only have the crawler left head back into the Thompson room, up the stairs, over the bridge and follow the path around to juggernog. Our survival chances just shot up. You can take 5 hits from zombies now. Go to next goal.
Once again you can camp at the Power area until you have 3,000 for Speed Cola. This is vital to reduce your reloading time especially with our big three guns. This is on the path from the power room back towards your starting point.
Exploit and Money time
So we should now have two decent weapons, Juggernog and Speed Cola. If you have 750 left after buying Speed Cola then head up the stairs in the Thompson room and turn right to unlock the door through to the Teleporter. Link the teleporter by standing on it and hitting X. You have about 20 seconds to run back to the starting location and stand on the other pad and press X to link. After linking, and after using the teleporter a Power Up will appear near where the Kar98K is. It may be useful to pick up. I would also suggest opening up the 750 gate on the other side of the starting location to open up a circuit on both sides of the starting point.
With the teleporter linked head back up that teleporter and go stand in and turn around. You will notice a room on your left, a walk way to your right where there is a mystery box location, and straight in front of you looks out to the bridge.
The exploit works where if you are standing in the back of this teleporter when the round starts no zombies will come from either the room on the left or the walkway on the right but only straight in front of you where the bridge is creating a nice line of zombies where you can use your high calibre weapons to mow them down. Try and aim head high of course. Throw a grenade out to create crawlers or throw out a monkey bomb if you are about to get rushed.
There are only three zombie Power Up drops that I would consider coming out of the teleporter for as this will start spawning zombies from the left and right and will probably require you to teleport in order to survive, see next paragraph. I would risk it for 2X, Max Ammo if required, or Instakill as it helps preserve your ammo and you should be able to stay in control with it.
If you get to a point where you're surrounded and have 1500 points which you should get before being overwhelmed with the right firepower hold X to teleport. If you have to do this you will have just enough time to grab the Power Up drop down by the Kar98K if its useful. Instakill would be great now or 2X or Max Ammo, even a Carpenter would be useful. Don't get a bomb. They will be swarming out from the Thompson room so head out the other way and back towards the Power area. Keep cool. You will probably have a couple in front of you to shoot. Once you are back at the power switch they will be funnelling towards you again. Get a crawler and mop everyone else up.
Obviously don't teleport if you don't have to.
Dogs and the exploit
By the time you get another wave of dogs you should be in the teleporter. This is a perfect place to get them as they still only come from directly ahead of you. Just be careful if you dash out to get the max ammo that you get back into the teleporter before the next round starts. If you think you are getting close to the last dog let them get a bit closer to you before killing them.
Depending on youy money supply and weapons you can now do the following.
1)If you need better weapons try the mystery box.
2)Optional - Buy the Bouncing Betties off the wall near Juggernog to lay down in front of the teleporter to give you that bit more destructive ability. Plant them before you shoot the last crawler. Remember be in the teleporter when the round starts.
3)Link the remaining two teleporters so you can pack a punch a gun.
If you link the remaining two teleporters then you will have to open the 1250 door by the power box and you can then no longer camp here. What you can do then is proceed past the bowie knife location and up on to the catwalk near that teleporter where the mystery box location is. You are potentially trapped up here so you really need monkey bombs or really good weapons to ensure you don't get over run here. You can throw grenades over the railing or towards the end of the catwalk to try and make crawlers.
Pack a Punch a gun
Once the teleporters are linked and you have 5,000 Pack a punch either the PPSh-41, MG42 or the Browning M1919 to make a really kick ass gun. Pack a Punching replenishes your ammo for this gun.
Get back up in the teleporter room and repeat the process getting more points.
You now have the firepower and strategy to milk some serious money to enable you to either pack a punch 4 more weapons or hit the box enough times to get the 3 wonder weapons.
If you go for the wonder weapons, hopefully you already have the monkey bombs. When you get either the DG2 or Ray Gun, this should be your second gun with your PPSh-41, MG42 or the Browning M1919 the gun you swap out for the third weapon. You will probably die in the next round but you'll have the achievement :D
**Important** make sure you are back in the teleporter before the round starts or you will get zombies coming from three angles. You can kill the crawler from upstairs in the teleporter room shooting down into the Thompson area and run back into the teleporter. Just be inside before the round number changes.
Its useful to keep save 1500 so you have the money to teleport but you should be able to earn it before you get in trouble.