Here is the full list of all 56 Welcome to Princeland achievements.
Master your Hunter mastery.
Master your Mine skills
Master your Ronan Sniper skills
Master your radiobomb skills.
Master your M4 skills.
Master your Railgun skills
Master your Rocket Launcher skills
Master your Magnum skills
Master your Grenade Launcher skills
Master your Flame Thrower skills
Master your AS25 skills.
Master your Grenade pistol skills.
Master your Rifle skills
Master your Suicide Bomb skills
Master your Tommygun skills
Master your Desert Eagle skills
Master your Spear skills
Master your Dynamite skills
Master your Hunting Rifle skills
Master your Baseballbat skills
Master your SMAuto skills
Master your Grenade skills
Master your Aug skills
Master your Revolver skills
Master your Knife skills
Master your Molotov skills
Master your Handgun skills
Gear up & explode a suicide bomb
Enter to Quarantine
Reached Rank 50
Master your axe skills
Master your Two Barrel Shotgun skills
Master your Commando Scar skills
4 players inside a vehicle
Reached Rank 45
Reached Rank 40
Take down a cargo plane
Reached Rank 35
First fly with Seat Copter
Master your Rusty Revolver skills
Reached Rank 30
Kill the Prince
Reached Rank 25
Master your Domdom skills
Master your Barracuda skills
Reached Rank 20
Hunt an enemy with Ronan Sniper
Reached Rank 15
Find & Open a Treasure Chest
Deliver a truck
Reached Rank 10
Open a hatch
Reached Rank 5
Reached Rank 2
First time on the driver seat