Here is the full list of all 18 Rocket Wars achievements.
Kill 2 enemies with a single Shotgun burst
Stay in orbit around the sun for a full 10 seconds without thrusting
Get a triple-kill with the Buzzsaw
Win a game of Survivor without dying once
Play 3 matches of any mode with a full lobby of people
Unlock your first ship
Unlock all 12 ships
Win a game of Nuke King by surpassing the leading player via the last Nuke explosion
Kill 3 enemies with a single Sniper weapon (across all 3 shots)
Destroy 30 mines
Detonate the Nuke without taking damage
Kill a player who has the Nuke within 1 second of him getting it
Kill 50 enemies
Kill 150 enemies
Kill 500 enemies
Kill 20 enemies by using the Pulse as a melee weapon
Kill an enemy by deflecting his own Sniper shot with the Pulse
Kill an enemy by deflecting a Buzzsaw