Destroy a single enemy.
Destroy only ten enemies.
Destroy just fifty enemies.
Eliminate 100 enemies.
Defeat 500 enemies.
Defeat 1000 enemies.
Eliminate 2000 enemies.
Destroy 5000 enemies.
Destroy 10000 enemies.
Complete the story.
Own all the parts.
Reach level 1.
Reach level 5.
Reach level 10.
Reach level 15.
Reach level 18.
Reach level 19.
Reach level 20.