Here is the full list of all 78 Hold The Dots! achievements.
Red U
Red V
Red W
Red X
Red Y
Red Z
Red L
Red M
Red N
Red O
Red P
Red Q
Red R
Red S
Red T
Red C
Red D
Red E
Red F
Red G
Red H
Red I
Red J
Red K
Green T
Green U
Green V
Green W
Green X
Green Y
Green Z
Red A
Red B
Green K
Green L
Green M
Green N
Green O
Green P
Green Q
Green R
Green S
Green B
Green C
Green D
Green E
Green F
Green G
Green H
Green I
Green J
Blue S
Blue T
Blue U
Blue V
Blue W
Blue X
Blue Y
Blue Z
Green A
Blue J
Blue K
Blue L
Blue M
Blue N
Blue O
Blue P
Blue Q
Blue R
Blue A
Blue B
Blue C
Blue D
Blue E
Blue F
Blue G
Blue H
Blue I