Here is the full list of all 34 Little Triangle achievements.
Tutorial completed
First death
Every single diamond
100 kills
500 kills
50 combo in credits screen
Every single money bag
1000000 diamond
Lava walker
All secrets uncovered
All hostage saved
All idle poses
All stages completed
500 death
1000 death
100 electrocution
Slipped into lava 100 times
Crushed 100 times
All stages cleared without dying (world 1)
All stages cleared without dying (world 2)
All stages cleared without dying (world 3)
All stages completed(factory chapter)
All stages completed(Egypt chapter)
All stages completed(forest chapter)
Get dizzy for the first time
Caught by the boss of the factory
Finish the opening scene
Play the arcade in stage of factory chapter and complete it
First time playing the arcade in a stage
Play the arcade in stage of egypt chapter and complete it
Watch the complete story ending
3000 death
Watch the complete animation for curtain call
NEW_ACHIEVEMENT_DESC_2_5