Open Steam or visit gog.com. Step 2: Type "Chicken Invaders 6" into the search bar. Step 3: Click "Download Demo" (Free). This downloads the game client (approx 500 MB). Step 4: Play the demo. Reach the first boss. If you enjoy the gameplay, click the "Upgrade to Full Version" button inside the game menu. Step 5: Complete payment via credit card, PayPal, or Steam Wallet. Step 6: The game instantly unlocks all 100+ levels. No second download required. No viruses.
Happy hunting, space cadet.