Here is the full list of all 30 Porcunipine achievements.
Win an Arena game with at least 10 skulls more than the other players
Make 2 close calls on different players with a single shot
Kill a player while dead
Play with 3 friends
Play practice mode as every porcunipine
Visit every arena in the game
Kill 5 or more enemies with a single shot
Kill the fastest wolverine
Collect a total of 666 skulls in the practice mode
Win a team game without ever killing your teammates
Win a game against a team of 3
Play as Blue porcunipine in Team Red or as Red porcunipine in Team Blue
Collect 500 skulls playing for team Red
Collect 500 skulls playing for team Blue
Win a round of Last Man Standing without killing anyone
Win a Last Man Standing game without ever breaking your helmet
Finish an entire Last Man Standing game without dying
Make a 3 players combo kill in Last Man Standing and win the round
Play one minute in the Arena mode without collecting any skulls and dying
Win an Arena game against 3 bots
Kill all 4 players (yes, including yourself) with a single shot
Kill the Blue porcunipine 100 times
Kill a player 10 times by bouncing a shot off a rock
Die inside the Pyramid
Stand still for 15 seconds
Stand in the snow area for 15 seconds straight in the Ice Age level
Activate switches 100 times in a round
Get stoned by a falling boulder at 4:20 pm
Reach 48 hours of play time
Earn every achievement in the game