Rule 1: Eliminate all alien invaders to progress through the levels.
Rule 2: Avoid enemy fire by maneuvering your character across the screen.
Rule 3: Collect power-ups dropped by defeated aliens to enhance your weapons.
Rule 4: Keep an eye on your health bar and collect health pick-ups to restore it.
Rule 5: Gather allies scattered throughout the levels to assist you in combat.

Movement: Use your mouse to move the cowboy character around the screen.
Shooting: The cowboy fires automatically; aim by moving the character towards the aliens.
Dodging: Quickly move the mouse to dodge incoming enemy projectiles.

If you enjoy this game, you might also like these games with similar gameplay.

Defeat aliens and collect the power-ups they drop to upgrade your firepower.

Yes, look out for heart-shaped pick-ups which will replenish your health.

Allies will fight alongside you, providing additional firepower and helping you defeat the aliens more efficiently.