Sonic Unleashed Cheats

Hungry Hungry Hedgehog (30): Eat everything in the world
Hyperdrive (10): Improve your Lightspeed Dash!
I Ain't Afraid of No Ghost (5): Someone is dealing with spectral troubles
Iced Hotdog (10): Eat all the hot dogs in Holoska
Kebab on a Bun (10): Eat all the hot dogs in Shamar
Ketchup and Mustard (10): Eat all the hot dogs in Empire City
Knockout Brawler (20): Smash, smash, and smash some more
Lay the Smackdown (10): Improve your Stomp!
Looking Better (25): Save the second continent
Oh, You Shouldn't Have! (10): Give a souvenir to the Professor
One More to Go (25): Save the sixth continent
Partly Cloudy (30): Collect Sun Medals
Picking Up the Pieces (25): Save the fourth continent
Pig in a Blanket (10): Eat all the hot dogs in Spagonia
Power Overwhelming (30): Create an unbeatable Werehog
Ring Leader (20): Gather Rings from all over the world
Sausage Fried Rice (10): Eat all the hot dogs in Chun-nan
Smasher (10): Get your Werehog level up some more!
Social Butterfly (30): Talk to people around the world
Speeding Ticket (20): Become the fastest thing alive
Still a Jigsaw Puzzle (25): Save the third continent
Still Broken (25): Save the first continent
Sunny (50): Collect all of the Sun Medals
That's Enough, Seriously (20): Give every souvenir to the Professor
Thrasher (10): Get your Werehog level way up there!
Wall Crawler (10): Improve your Wall Jump!
World Savior (100): Complete the game

Eggmanland Hub World
In order to unlock the hub world for Eggmanland, you must defeat the final boss and beat the game.

Walk through walls
If you go up to pretty much any wall/door as a werehog, pressing X Y Y for the combo, followed by shielding, will let you pass through the wall.