Here is the full list of all 33 Dot to Dot Puzzles achievements.
Finish 5 pictures
2,500 dots connected
Finish 2 pictures
Pic greater than 1000
1,000 dots connected
Finish and Color
Pic greater than 500
500 dots connected
Connect 100 Dots
Connect 10 Dots
5,000 dots connected
10,000 dots connected
20,000 dots connected
Unlock Star Picture
40,000 dots connected
75,000 dots connected
125,000 dots connected
200,000 dots connected
300,000 dots connected
Finish 10 pictures
Finish 25 pictures
Finish 50 pictures
Finish 100 pictures
Finish 150 pictures
Finish 200 pictures
Finish 250 pictures
Finish 300 pictures
Pic greater than 3000
Pic greater than 4000
Pic greater than 5000
Pic greater than 6000
Pic greater than 2000
Pic greater than 7000