Here is the full list of all 21 Intralism achievements.
Play multiplayer game with other player
Up your profile to level 10
Create new level in editor
Complete level in multiplayer
Play multiplayer match with workshop level
Play multiplayer game alone
Find authors list
Lose within second after checkpoint and resume from it
Find your items
Launch Intralism
Subscribe to any level in workshop
Collect at least one item of each rarity
Complete 10 (different) official maps in normal mode
Recieve your rank
Win multiplayer match
Swich workshop filter in maps list from "trend"
Play 5 maps in relax mode