Here is the full list of all 36 Besiege achievements.
At least 2 players joined your server
Join over 10 servers
Defeat 1000 AI units
Get hit by lightning
Complete Tree of Akhmora without using Crossbows, Cannons and Explosives
Complete Kahraz Village without using Cannons, Crossbows, Drills or Saws
Beat the Southern Shrine by primarily using fire to kill the birds
Beat Old Howl Battlefield while having blown up all the bombs
Complete the Mountain Barrier without explosives
Complete Old Mining Site without pressing a key
Complete Perimeter Wall without pressing a key
Complete the Revolving Monolith without using Grabbers
Ring all 3 Awakening Bells at the same time
Beat the Consumed King without using mechanical blocks
Beat Scouts of Tolbrynd without cannons, flamethrowers or crossbows
Complete Standing Stone without using armor
Beat Queens Fodder without using fire or explosives
Complete a player-made map
Share your machine with the whole world
Build your first level using the level editor
Complete a campaign level with under 3 blocks
Complete a campaign level under 2 seconds
Complete Krolmar
Complete the Campaign
Lift the boulder in Stock Tower 10 units off the ground
Complete Towering Eye without ever being hit
Conquer Valfross
Reach enough altitude to freeze your machine
Conquer Tolbrynd
Steal the Duke's knowledge in under 2 minutes!
Put out a burning block using water
Destroy the Duke's freighters without flying blocks
Conquer Ipsilon
Travel at speeds faster than is sensible
Subscribe and download someone else's machine
Set yourself on fire