Here is the full list of all 17 Find this! achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Have not found the last one from more than 4 items
Have not found a single item in 15 seconds
Find all items 5 times in a row on medium difficulty
Collect 300000 points
Collect 250000 points
Find all items 5 times in a row on easy difficulty
Find the last item in the last 5 seconds on hard difficulty
Find all items in 3 seconds on hard difficulty
Give up and start a new round
Find all items 7 times in a row on hard difficulty
Find all items in 5 seconds on hard difficulty
Collect 150000 points
Find all items 5 times in a row on hard difficulty
Collect 80000 points
Collect 25000 points
Find all items without hints on hard difficulty
Have not found a single item per round