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