Begin the game by selecting your preferred difficulty mode from normal. Move your character through challenging levels in each mode. Utilize the mouse to focus and click to launch your weapon at the invading robots. Pick up coins and acquire first aid kits or more powerful weapons from the in-game store to boost your survival chances. Adjust the mouse sensitivity in the settings for improved control. Watch out for your health bar; activate first aid kits when required to regain health. Finish all levels in a difficulty mode to reveal the next challenge. Survive the robot attack and protect the world.