CrossfireX

This achievement should pop upon the completion of your final other achievement which will most likely be the achievement for 100 games. A couple basic tips..

- Play Point Control on GR Tower which is under the selection of "Modern"
You want to do this as matches can be quick (Under 10 minutes) and there's plenty of respawns
-When spawning in put your points into 2 down and 1 left. This will give you quick fire rate as well as health regen. This is good if you can consistently win gun fights so that you can heal up for your next.
-If that doesnt suit you try 2 points left and one point right. So that your bullets deal more damage and you can kind of cheese by having a shield if you switch to your secondary by pressing
- Always save your xp up to 2000 and choose to buy into the boogieman. You by default are able to heal by sitting outside of combat and you get 600 hp as opposed to the normal 120 making it pretty hard to lose 1v1s unless your opponent is also a boogieman.

Tips for headshots
- Aim for the enemies mid or upper chest based off of your weapons recoil. This will allow your recoil to jump to their head making for easier headshots without aiming for something as small as their head.
-Snipers are also good as they will guarantee 1-shot headshot kills if you're accurate enough
-I reduced my sensitivity all around by about 20% because of the crazy unnecessary aim acceleration which can certainly be frustrating at first.
-Crouching will increase accuracy and reduce spread making for easier aiming and if you add this to crouching behind cover it makes it harder for you to be killed as well

Wins will count as 2 games played
Headshot kills will count as 2 kills for the kills achievements
And penetration kills will count as 2 kills for the headshots. These are incredibly inconsistent and pointless to try for.

Edit: To add to this other guides write in other modes such as NANO or TDM being quicker modes depending on how many people are afk or actually playing. Try to find whichever mode you have the most luck in as far as the matches played goes as it can differ for everyone. I still stand by Point Control being the fastest for everything else though.

EDIT: This achievement is known to be very buggy - if you don't want to risk an unfinished game due to this achievement not working as stated many times in the comments, don't start this game.

You get this after completing all other achievements.

If you are interested in a fast achievements guide check the link below: