To start playing Alien Invasion, simply visit 4J.Com and look for the game under the free games section. Click on it to begin your journey as Earth's last line of defense.

The primary objective in Alien Invasion is to eliminate every alien threat that launches a full-scale invasion against Earth. You must secure victory in this cosmic battle for the survival of humanity by defending Earth from relentless attacks from all directions.

Yes, Alien Invasion features multiple stages set across various locations in space, each presenting unique challenges and enemy types. Progress through these stages to advance in the game.

Unfortunately, character customization is not available in Alien Invasion. The focus is on the gameplay and the defense of Earth against alien forces.

While Alien Invasion is designed for a general audience, some scenes may be intense. It is recommended for players who enjoy action-packed space defense games.

Alien Invasion is available for free play on the web through 4J.Com. Ensure you have an internet connection to access the game.

Practice makes perfect! Try experimenting with different defense tactics and weapon upgrades as you progress through the game. Learning the patterns of alien attacks will also help in improving your defense strategies.

There is no dedicated tutorial, but the game provides basic instructions at the beginning. As you play, familiarize yourself with the controls and the layout of the game to get the hang of it.