Sniper: Ghost Warrior

This is not difficult at all. To make it easy on yourself, host a game of Team Deathmatch on Canyon with the kill limit set to 5. A win should take no more than a minute (assuming you're the one winning). This must be done in a Ranked Match.

You can also boost this using the same method (which you may NEED to do, due to dwindling number of players) by having at least 3 of your buddies join your match and taking turns killing each other. Have the team getting killed run to the bridge in the center of the map and pick them off quickly. You can finish a game in under 30 seconds.

(Edit) To clarify: You do NOT need to have the most points, you just need to be on the winning team. You can check your progress by viewing the achievements menu from the main menu.

This must be done in RANKED MATCHES. You are able to boost this achievement with friends. If you want to boost set the score limit as low as possible and play team deathmatch on canyon. If you want it legit I would suggest playing team deathmatch as you have a higher chance at winning(50,50).

NOTE: You can invite your party to a ranked match by pressing start and then going down to invite Xbox Live Party.

As of October 2020, the Online Servers for this game are still up and running. For safety pre-cautions however, I would advise getting the Online Achievements done for this game as soon as possible, in case of a possible Server Closure.

Before I start talking about this Solution, I would like to give Credit to my Friends RegionalRagger & Angelus for all of their assistance with this game.

There are only 5 Online Achievements for you to get in this game that require Ranked Matches. But in order for you to start a Ranked Multiplayer Match for this game, you will need a minimum of 4 Players or Dummy Accounts, including yourself. If you have multiple XBox 360 Consoles with Gold Dummy Accounts and extra copies of the game, I recommend using them to Speed Up the Kills & Timeframe to get the Achievements. Idle Accounts do not get Kicked in this game.

Organization

I recommend you go for this Achievement first, before you go for this Kill related Achievement. Because as your progress, you will get Kills, whilst you are winning 50 Rounds of Multiplayer...



Now as said above in the other Solutions, if you are the Host, your Killcount towards the Achievement is Unsually Doubled, meaning that it takes less time for you to get the respective Kill related Achievements. So with this in mind, if you are playing with a group, you will all need to decide who is going for the Kills. Once decided the Host needs to setup a Ranked Match by going into...

Create A Match
Ranked Match: Yes
Match Type: Team Deathmatch (Fastest Game Mode)
Map: Canyon
Public Slots: 6
Min Players To Start: 4
Rewards Limit: 5 Kills
Time Limit: 15 Minutes
Show Players On Compass: On (Big Advantage)
Auto Kill When Away: Off (Allows Accounts To Idle)
Friendly Fire: Off

Tip: Some of these Features might be Turned Off under "Advanced Options". They can be turned on by simply pressing the or button.

Once it is all Setup, press the Button to Start the Match.

Now once you have Setup your Match, have everyone else/accounts to join the Match by either Searching for a "Quick Ranked Match", or searching under a "Custom Ranked Match". You may need to use both features in the game, cause believe it or not, there are still a handful of Randoms that play Online on this game time to time.

Tip: You can check who's joined your match as well by pressing the button.

If you want to get everyone to be Speedy & get the Matches done faster, I recommend choosing the "Light Recon" Class, because they are the fastest in Speed. You can change this at anytime by pressing the button when your in the match.

Once the amount of People have successfully entered the Match, Host can start a Countdown and let the game begin.

Note: Once the Host has Started the Ranked Match, no one can Join or Re-Join the Match if they get Kicked.

Boosting Method

Team Going For The Win: Pretty Easy! As a Team, simply run across the Bridge to the other side of the Map and get a total of 5 Kills with yourself and your partner. It's up to you all if you want to dedicate one person going for the Kills. Or both people and getting the Matches done as fast as possible.

Tip: A fast way I found out when getting these Rounds done quick is to always have the Host win, regardless of what Team they are based on. Because the game does do Auto-Balancing on occasions. So choose 1 person to be the one what Wins all the time, then when they get the Achievement, swap the Hosting and let someone else be the charge-hand of Winning Rounds all the time. This should speed up the process. Obviously if you have Dummy Accounts, this doesn't really matter if you have less people going for the Win.

Team Not Winning: This is easy for you too. You can either represent yourselves to your opponents, and get shot in the Ass. Or you can sit idle for the duration of the Match and let your opponents pop over to your spawn location and get a Team total of 5 Kills to finish the match. What you do, is up to you.

Once the Match is Complete, you will be returned to the Main Menu. The Winning Players with the Win will have 1 / 50 Round Wins done, towards the Achievement. Rinse and repeat all of the above, until everyone gets the Achievement.

Progression

When you get returned to the Main Menu of the game, there is a feature that allows you to check your progress, towards the related Achievement you are going for. It is located under "Achievements". Simply click on it and scroll down to find the Achievement's name. Once you've found it, a Bar will appear from Left to Right, showing you your progress you have done towards getting the related Achievement. So keep checking this on a regular basis.

Conclusion

With all of the above Methods applied, it should roughly take about 2 - 4 Hours for one person to get 50 Round Wins, and the Achievement. So if there's a Group of 4 of you, wanting the Achievement, it will take around 8 - 15+ Hours for you all to get the Achievement.

Hope all this is useful. Good Luck!