Tips and Tricks
To unlock new weapons earn a good amount of coins and then visit the store. There are a variety available, which you can purchase and upgrade over the course of the game.
The best weapon is the flamethrower because not only is it sufficient for hitting enemies from a distance, but it's also quite powerful. The downside is that it loses juice rather quickly.
When the UFO appears, simply shoot it, and your precious power-up will reappear. Tap it to add the power-up back to your collection.
When you see a rubber ducks and gifts appear in the water tap them quickly to reveal coins and power-ups that you can collect, and add to your overall collection. If you tap the space around them instead of directly, you'll accidentally shoot your weapon and have to reload.
The shotgun is a fairly good spread weapon, so aiming for two enemies at once is a great tactic just try to tap the space between them. Also try to time your shots for when enemies are closest to you. This makes your hits more critical as they get closer.