Here is the full list of all 34 Alkali achievements.
Complete the tutorial
Complete the Grand Mesa world
Complete the Ice Caves world
Complete the Rainforest world
Complete the Facility world
Complete a dark world level
Complete all regular campaign levels
Complete ending A: Alkali
Complete ending B: Breakout
Complete ending C: Comrades
Enter a secret portal
Find a glitched diskette in the campaign
Unlock a journal entry
Unlock half of all journal entries
Unlock all journal entries
Acquire all campaign diskettes
Pick up 5000 metal chunks in the campaign
Reach 500 mass in the campaign
Reach 25 000 total score in the campaign
Reach four times maximum running velocity
Travel 42 195 meters
Complete a campaign level in 40 seconds or less
Complete a campaign level without dying
Complete the game in 1 hour or less
Stay airborne for 10 seconds in a campaign level
Spend 60 total minutes airborne
Spend 15 total minutes on fire
Spend 10 total minutes underwater
Plunge into water while electrically charged and on fire
Die from dashing or double jumping
Die once to each hazard in the campaign
Destroy a Living Remnant
Complete a custom level
Obtain all achievments