Left 4 Dead 2

**only if willing to boost**

find 3 other friends. run 2 controllers per xbox. separate yourselves into two teams of four (with your guests). pick a more obscure level with higher round setting (less people playing). then hope that you find your other group. i did it this method and matched up with my friends on our 2nd try. then, once the game is over and one group has the achievement, select rematch, and the other group of 2 will get the achievement. too many people quit out of legit matches, got fed up. good luck.

i chose hard rain, 5 rounds, local server. most people online seem to be playing 1 or 3 rounds, so less people will be searching for those settings.

First you must find 3 other friends that are willing to play a game of scavenge or versus. Then while on the main menu click on which ever mode you want to play, then look down the list of options for "Team Versus" or "Team Scavenge". Press this option and it will prompt you to start your own team, do so and it will take you to a lobby with 4 slots. Invite your friends and hope that your skills are better than the people you are matched with because you must win the match in order to unlock this achievement! I'm not sure but all 4 people on each team might have to stay in the game or else the achievement might not unlock... So I recommend scavenge since the games are way quicker than versus and you stand a better chance of everyone sticking around for the whole game, I might be wrong about the last bit though.

I recently got this during a dedicated boosting session, and we had some difficulty getting it going, so I figured I'd add some notes here from my experience to clarify some things for anyone else trying this.

1) The matchmaking is regional. This means that the two lobby hosts need to be in the same region e.g. country, or possibly "Europe" in general if that's applicable to you. (Thanks to comments from GutshotStraight in one of the other solutions for this tip).

2) Our initial lobby hosts were running two Xboxes behind the one router in the same house, and we were not able to link up a session. You may have problems if you're trying the same thing.

3) You can definitely have guests involved on second controllers (confirmed by other solutions here).

4) Choose "Local Servers". This won't stop you matching up, but it will make the connections a bit more reliable, at least for the hosts.

5) Scavenge is by far the quickest way to boost this achievement, even with a best of 5 rounds match. We picked best of 5 to minimise the chances of being matched up with a random group. The side who is doing the winning should just collect 1 gas can or whatever and let the time run out, and then kill the survivors when it's their turn to play the infected. If the "winning" team plays the infected first, when it comes their turn to scavenge they will only need to make a single collection and the round will be over. It will go quickly.

6) One or both of the lobby leaders may get booted during the loading screen. I believe this is due to some caching issues with the maps. I recommend picking one of the basic maps such as Dead Center on both systems, and if the lobby drops out the map should hopefully be cached anyway and the second attempt should be fine.

7) Loading the game up initially will take AGES. We had to wait several minutes while one of the hosts sat on a loading screen, then the rest of us went to a loading screen, then a few minutes after that it started up. As long as it says it's actually found an opponent, don't worry, be patient, it should get there in the end.

8) A "team" consists of a full lobby of 4 people. You can't get this achievement by joining random games as a loner, you need to be in a full lobby from the start.

9) I am unsure if staggering the start times of the two lobbies is necessary, but we did this and it worked. Your mileage may vary. If you have trouble getting connected, try delaying the start of the second lobby by 30-60 seconds.

10) If the game doesn't find the other group it will probably sit in a spinlock looking for games, and for some reason you can't cancel the search. The only way to get out of this was to leave the lobby. It's a PITA, but that's how it seems to be. You will need to recreate the lobby or rejoin the old one, which will have a new lobby host. Incidentally, there appears to be no way to change the host of a lobby short of the current host leaving.

That's about all I can think of, and I hope this is helpful.

Get 3 people who know how to play. Start up a match in Dead Center (the car level). When you are the survivors, have two people go to the top floor and work their way down to the bottom, throwing the gas cans down to the other two members of the team. For the two filling the car, throw pipe bombs when you hear the horde coming. Keep the gas cans out of the spitter acid as they will blow up and your teammates will have to go back for them when they respawn.

When you are the infected, smokers and jockeys immediately go to the third floor and wait for survivors to come to you. When they do, gang up on them. Boomers wait behind the car until a survivor show sup with a gas can and puke on them. The resulting horde should keep them from emptying the can. Chargers wait by the elevator until the survivors go for it, and then charge all the way down at them by the car. You should be able to grab them and carry them to the far wall which is hard to hit by other survivors upstairs. Spitters should sit on the second floor above the car and spit 2-3 seconds before a survivor gets close enough to empty their cans. Hunters should try to catch a lone survivor or gang up with a smoker or jockey on the gatherers.

As the survivors you should have no problem getting 16 cans each time, and then you just need to keep the opposing team from doing the same. Keep in mind hat playing against teams of people usually means they will be well coordinated together, and is much more difficult than random matchmaking.

STRENGTH IN NUMBERS - 15G (Original Achievement)

Difficulty: Easy

Estimated Period of Time: Varies depending on other players
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To get this Achievement, you'll need either 7 other players or less depending if you and others have multiple controllers.

Next, you and one other person must create a "Team Scavenge" Match (you can find this by choosing Scavenge on the Main Menu, then choosing Team Scavenge instead of Quick Match etc.) Then you both must invite 3 other players to your lobbies. Once you both have all of your players ready, set your settings to the same map (Dead Center, Atrium, Best of Three, Official Dedicated for example), then both of you start searching. As this game is more or less dead, It's extremely unlikely that you will find any other Teams of 4 besides yourselves.

Once all eight of you are in the match, have Team 1 score one gas can, then kill them off with Team 2. Next, have Team Two (Now the survivors) get killed off instantly without scoring. Repeat this allowing only Team 1 to score each round until they win. Afterwards, repeat the entire process for Team 2's win.

Start by finding 3 other players who each have a second controller.

Then form 2 teams with 2 main accounts and 2 guest accounts in each team, then each team launches a team scavenge search, so that you are in the same game.

Once all 4 of you are in the same game, one team wins the game, which will unlock the achievement for 2 players, all press start to start a new game, the other team wins the game.