Occasionally, a box symbol will appear on top of the head of a planet's inhabitant. This indicates that it wants you to deliver the box to another planet.

1. Tap on the box button in the bottom left corner of the main page to head to the inhabitant's planet.
2. Wait for your spaceship to arrive at the planet (you can use the Boost function below the box button to speed things up)
3. Tap the box above the inhabitant's head to accept the package.
4. Tap the box button in the bottom left corner once more to find the target planet and wait for your ship to arrive.
5. Tap the box above that planet's inhabitant's head and the delivery mission will be complete!

These adorable alien inhabitants will give you a few gold coins or energy cubes as a reward! Completing delivery missions is an excellent way to collect energy cubes!