Here is the full list of all 12 Darkour achievements.
Beat level 20.
Beat level 40.
Beat level 60.
Beat level 80.
Beat level 100.
Get an A+ in levels 1-20
Get an A+ in levels 21-40
Get an A+ in levels 41-60
Get an A+ in levels 61-80
Get an A+ in levels 81-100
Collect 16 light bulbs.
Collect all 32 light bulbs.