Visit the crystal planet 100 times.
Visit the desert planet 100 times.
Visit the icy planet 100 times.
Visit the lava planet 100 times.
Visit the mechanical planet 100 times.
Visit the grassy planet 100 times.
Re-fuel 50 times.
Unlock the bus.
Use a hint 50 times.
Use a hint 100 times.
Complete a level using only hints.
Restart a level 50 times.
Restart a level 100 times.
Restart the same level 10 times.
Finish a level without restarting or using a hint.
Drop off 50 passengers.
Drop off 150 passengers.
Drop off 300 passengers.
Drop off 500 passengers.
Reach Level 25.
Reach Level 50.
Reach Level 75.
Reach Level 100.
Finish Intergalactic Taxi Co.
Click on the Hula girl in the level select menu 10 times.
Click on the sun 10 times.
Click on a UFO 10 times.
Click on the taxi or bus 10 times in a row.