Here is the full list of all 25 Boney's Research On Humans! achievements.
Snap a picture of all the regular enemies
Finish the game
Snap a picture of all the monsters
Get S tier in all the stages in regular mode
Hide in all the possible places
Collect all the research items
Finish the first level under 45 seconds in time mode
Snap a picture of a human
Hide for the first time
Find Captain Viridian's costume
Find Green Cap's costume.
Find Tim's costume
Find Death's costume
Find Diggin it' Drarf's costume