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