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