Unlock Worlds
"Angry Birds HD" offers a number of different worlds for players to explore, with each world containing separate levels. Players must successfully complete each level in order to advance to the next. However, employing a simple game cheat can unlock all the worlds without having to play through every level. Load "Angry Birds HD" and go to the world selection screen. Center a locked world on the screen and then push the iPad's back button to exit the program. Now reload the game. When the game loads, rapidly tap the screen's "Play" button. This should place you inside the select screen for all the locked worlds. Passing the first level of each world will now unlock the entire world.
Bird Chirp
After you advance deeper into the game, you'll be allowed to use a massive red bird that uses its size and weight to destroy pig structures with sheer brute force. While the big red bird doesn't possess any hidden talents, such as dropping eggs or exploding, tapping the screen after you've launched the bird will make it chirp a battle cry. Earning three stars on every level in Worlds 1 through 3 will also grant access to the game's soundboard, letting you hear all sound effects.
Golden Eggs
Players may also collect special Golden Eggs as rewards for completing certain tasks. The Golden Eggs open up extra bonus levels. Players can find Golden Eggs hidden throughout the game. To unlock Golden Egg Level 1, earn three stars on every level in Worlds 4 and 5. Tapping the sun pictured on the game's select screen is enough to enter Golden Egg Level 2. Popping the yellow balloon in the lower right corner of Level 6-14 will open up Golden Egg Level 10. Breaking the boxes in the far left corner of Level 8-15 permits entry to Golden Egg Level 13. The game includes 17 Golden Egg levels, so explore all aspects of each level to discover other hidden eggs.
Completion Bonus
Rovio continues to add upgrades and new add-on levels for "Angry Birds HD," with at least 270 levels available to players. Successfully completing each level defeats the game and earns you a completion bonus, which unlocks all the game's birds and extras.