To unlock the (all chapters, the final boss, the secret ending, and online co-op mode), you must purchase a license key. This is how InterAction Studios continues to update the game with new content, seasonal events (like the Easter Special), and bug fixes.
| Feature | Trial Version | Full Paid Version | | :--- | :--- | :--- | | Campaign Chapters | Chapter 1 only | All 15 chapters | | Final Boss | Locked | Epic final battle against the Dark Chicken | | Online Co-op | Disabled | Full 2-player co-op | | Weapon Prestige | Up to Bronze level | All Prestige levels (Silver, Gold, Platinum) | | Easter & Holiday Events | Disabled | Full seasonal content | | Secret Ending | No | Yes | Download Chicken Invaders 5 Full Free Version