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