Here is the full list of all 20 Nyan Cat: Lost In Space achievements.
250 enemies eliminated with Nyan Love
Ran 25 seconds without collecting any food
2000 bombs deactivated
5 times jumped over a doggy in a game
Jumped on Gold Platforms 1000 times
Played 10 times on Nyan Cat City theme
100 Cow items collected
Played in a world other than Space
42195 meters completed
Ran 1000 meters without touching any kind of enemies
5 pills collected in a game
20 enemies eliminated with Nyan Love
A UFO abduction survived 100 times
100 bombs deactivated
x250 score multiplier reached in a game
Tac Nayn touched 9 times
Played with a skin other than NYAN CAT
Stayed on the highest platforms at least for 30 seconds
A UFO abduction survived
Stayed on the lowest platforms at least for 30 seconds