Finish the Ant Hill Entrance level.
Finish the Hatching Chambers level.
Finish the Overgrown Outpost level.
Finish the Flooded Wilds level.
Finish the Ant City level.
Finish the Sewers level.
Finish the Laboratory level.
Defeat Runnella.
Defeat Konna.
Defeat Mato.
Defeat Doctor Antstrong.
Get your eyeball back.
Defeat Mamoth.
Defeat Great Wisp.
Defeat the Fly Twins.