Aliens vs. Predator

First of all to clarify the requirements :

- It must be Ranked
- You must be the ONLY survivor left when the timer runs
- You have to survive till the time runs out! If everyone becomes infected, you will not get this achievement
Edit : (Credit to Crowned Legacy) - The host cannot quit out of the match either, otherwise you wont get the achievement

This is actually quite difficult to get, as by the end you will have
5 to 11 Aliens running around the map trying to kill you. Really,
the best solution is to hide, as I have tried numerous
times to get this through fighting till the end but surviving the final
30 seconds is incredibly hard unless you are godly.

So without further ado, here are the hiding spots I used:

Ruins : Take cover in one of the zigguruats on the edge,
and hide in the top corners. If you can, snag some grenades, they will help.

Gateway (Thanks HybridPK) : Go to where the crashed ship is and head up to the sniper rifle. Stand there collecting respawning ammo, and picking off the aliens if they get too close. Once your the last one or two, run into the tunnel on your left hand side and pray. And shoot. Dont forget to do that.

Pyramid : This one is a mixed bag due to all the sliding doors. This is where I got the achievement, though more through luck than anything, I think Ruins is more consistent. Anyways, you want to go to where the predator weapons spawn with the moving stair cases, and hide in a corner next to the sliding doors. If you can, get some grenades as well. The sliding door will slide shut leaving you at a dead end occassionally, leaving you with one path to aim down. When it opens you must be more alert.

Well there you go. The other maps I havent found decent solutions for, and in my opinion are a bit harder. But remember this takes a lot of luck, it took me a coupel of hours to find the best combination for me. Good luck :)

This can be a truly horrible achievement to get, it may be pretty time consuming due to the rather limited number of people playing so getting a game can sometimes take a while, fortunately this is a plus in as much that you can get a game with only 4 players, clearly only 3 aliens is a much easier prospect, as has been said by others find a good hiding spot and grab weapons, grenades are good however at close range you can blow up yourself as well as an alien so I favoured the shotgun as the secondary fire with both barrels is pretty much an instant kill at mid rage tho beware of acid splash, it took me about 10 tries to get this over the course of a few days only in two was I lucky enough to be in with a chance as sometimes you will become the Alien ruining that attempt, try not to let your fellow marines spot your hiding place as they will know right where to go, I got this on ruins camping out in the sunken area with the tree just in a corner with my light off and shotty at the ready, I was in a game with 5 others and fortunately they were all on the other side of the map when I heard the last man standing message they found me with 10 seconds left and I managed to take out 3 Aliens and even tho number four started to beat me down time was on my side. So patience, a decent aim under pressure and a good slice of luck was what I needed, persevere and you will eventually get this with a big cheer, but don't worry as every fail will net you exp for any kills you get and the leveling up as a looong road.

First off, make sure you search for a game with only 8 players. Sure, 12-18 players is more fun but you aren't going to survive with 17 aliens running after you.

Personally, I tried getting this achievement for weeks, trying various hiding spots and weapon combinations. The winning formula came courtesy of the map 'Temple' and here's how I did it:

1) Collect as many grenades as you can.
2) Head to the central structure and face where the waterfall is facing.
3) Keep looking left until you see some stairs leading up to a wall.
4) Run to those stairs, put your back against the wall and pray.

From past experience I have learnt not to run when "Last Man Standing" is announced. I held my ground and luckily enough only one alien found me for the entire 30 seconds. It's safe to say that he was dealt through the medium grenadage!

It might be something to do with the colour of the wall behind you that masks the red outline somewhat but all I know is that out of 7 aliens only 1 saw me.

Hope I helped.

Unfortunatly, this one is affected slightly by the 'random factor' - try to start an infestation match with 4 people (the lowest amount) after 30 seconds of playing one random player will become an alien (if that player disconnects because they're a sore loser - another random player will be chosen) the way i did it is to try to stay on your own and hope the alien(s) go for the group of marines that always seems to appear. If you are the last remaining marine, you have to survive 30 seconds - take the 'hiding' approach because running never seems to pay off and aliens can see your 'scent' through the walls e.t.c and they're a damn sight faster then you. Try to find a bright place to hide in so the said scent is more difficult to see. Chances are, the aliens are running around frantically so any movement could be costly, some people have been known to quit as soon as they become the alien so just pray or something and you should get it eventually

Be-aware that as of February 2016 the online for this game is still popular with randoms and boosters alike so you may have some conflicts when you are trying to go for this achievement.

This is a very annoying achievement because unlike most of the others, it cannot be done if you are placed in a group with some other players/boosters. The reason is because the Infestation game mode will be faded out and you cannot access it unless you search individually.

The minimum amount of players needed to start a match towards this achievement is 4. But the problem with this game mode is that if everyone lives in different regions, it will be close to impossible to meet up with each other. So you will likely need at least 2 people in a boosting group to help you search for a match that live in the same region as yourself.
So once you have at least 3 people including yourself that are available to do this game mode, everyone needs to individually go into Ranked Match, Quick Match and then choose Infestation. When choosing the amount of people you wish to look for I recommend 8. Only choose 12 if you have a hard time finding each other (this may increase random threat).

Now the online matchmaking for this game is extremely difficult because when you search for matches, you will have no idea if you are searching with your boosting friends or not and you won't find out until you are on the lobby screen. You can however keep in contact with you and your boosting friends by saying how many people are on their screen when searching. If it's the same it will likely be you've all found each other.
Eventually after a short period of time the game will start counting down and reducing the amount of players need to start the match. Randoms can join your match still and they can do so until the match is loaded. When the game reached "0 Players Required" you will have a lobby. You have 30 Seconds then to choose your characters, vote on maps and your skins for the characters. For map-wise I recommend Refinery, The Gateway or The Jungle as they seem to be the smallest.

Now here is the important part. If everyone's ready they need to press the button to ready up and then they will have a tick on the left side of their gamertag. If everyone readies up, the match will load instantly and the 30 second timer will stop. This will load up the match and you will also prevent random players from joining it from here on out.

When all of you are in the match you will all start off as Marines for 30 Seconds. After the time duration one of you will turn into an Alien. If you are the Alien at this point of the game, you cannot go for the achievement and you will either have to let someone else go for it, quit the match or finish it and get a bit of XP.

Whoever wants the achievement needs to avoid any Alien contact completely because if you die, you will void the achievement. If you are boosting you first need to communicate because anyone playing as a Alien will not know which Marine to attack or kill. Signal the player who is the Alien by telling them where you are, what skin character you are, if you are standing or crouching etc. Now with this in mind the player who is the Alien can go ahead and kill the other people that are not going for the achievement.
When all of them except for the last Marine are dead, another timer will begin in which that lonesome Marine must survive the duration. If they do they will win the match and get the achievement. If they don't then the whole match is a waste of time and another one must be done in order to get another opportunity.

Note: Discovered by my friend Spangles21, if you play as a Marine and commit suicide, you will respawn as an Alien.

Once the player who wants the achievement gets it, rinse and repeat all of the above until everyone gets the achievement. As long as you don't get assigned as an infected at the start of the match and everyone co-operates with proper communication, this achievement is do-able.

Good Luck!