Rocket Wars

This is probably the toughest achievement to get because it requires luck, timing, and coordination. In Deathmatch, you'll need to wait for a Nuke powerup to spawn, and then have someone grab it, and then kill that person within one second of them grabbing it.

The way I did this by myself was to use one ship and fly around until I got a sniper weapon. Then I just flew around with that ship avoiding other weapons so I'd keep my sniper, all the while waiting for a Nuke to spawn. Once it finally does, fly within view of it and then press and hold and aim your laser sight directly at the nuke powerup. Now, while still holding down on that controller, grab another controller and put yourself in orbit to drift towards the nuke. As soon as that player touches the nuke, release on your first controller to immediately kill them. As long as you do it immediately (within one second) then this achievement will unlock.

It may sound a little awkward to do but I had no issues. The sniper is very accurate and reliable, so as long as you're aimed right at the nuke then you should have no problem getting the instant kill.