Comet Detector
The Comet Detector is the best item to upgrade as much as possible early, during the first planet if possible. It remains useful throughout the game. Try to upgrade it to at least level 10 early, focusing more on Speed instead of Rate.
Energy
The energy obtained by collecting items after comets are destroyed can be used to restore the planet as well as purchase upgrades. Upgrading the green level of the planet will also make more powerful comets appear. Manage your energy and balance the upgrades. Once the planet has been fully restored, you will begin a new restoration cycle with the green level dropping back to zero. However all remaining energy will be brought over. This makes it possible to quickly restore the new planet if enough energy was saved to purchase the more important upgrades immediately.
Weapons
When starting a new game, concentrate only on the missile to save money. The missile is usually the best option. It takes down all comets and earns the most coins. The cannon is the next best choice if you are not strong enough to destroy the comets with other weapons. It provides a chance for them to drop items before they explode. The laser is only useful when you get a lot of packed comets, however the missile can also handle that task. To take down comets, shoot missiles at regular intervals at the left side of the screen. As soon as a comet enters the right side, the missiles will home towards it, giving you a few extra hits.
