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