Unlock Gene Simmons and Secret Level
Complete the Story Mode on Normal difficulty to unlock Gene Simmons from KISS and the "Hotter Than Hell" level. (In this level, find and grab the floating KISS letters to unlock a new video. You don't have to collect them in order. Collect the letters again to watch the band perform "God of Thunder" on the virtual stage.)

Unlock All Movies
Enter digivid in the Cheats Menu.

Unlock Pedestrian Skaters
Find every Gap in the game (including in the hidden levels).

Create the Hulk
Face light skin 2
Turn skin colour lime green
Then make him shirtless
And give him denim trousers and turn the purple
Then give him black hair
Name him Hulk
And thats you

T.H.U.G. Music Code
Enter "holeshot" on the cheats menu.

Unlock Hangar Level
Go to Moscow and find the brown building near the tanks. Go around until you see the side where it is connected to X-mas lights. Climb up and grind the ledge toward the big building opposite of the tanks and jump into a window. Inside is the item that unlocks the level.

Unlock School 2 and Venice
In the New Jersey level, go to the train station. Where the rails are at, on the left ramp in the middle column there is an item high above the ramp. Take the rail down to the ramp to get more speed so you can reach the item. (Or, climb on top of the awning which looks like a little white ledge, and walk along it and around the corner.) Get the item to unlock the School 2 level.
In the Hawaii level, find the tiki statue. Jump into its mouth and ride down the tunnel to the end. Get the item to unlock the Venice level.

Unlock Iron Man
Beat the story mode to unlock Iron Man from Marvel comics.

Unlock T.H.U.D.
Beat the story mode on sick difficulty to unlock T.H.U.D.

Perfect Manual
Enter "keepitsteady" on the cheat menu.

Unlock Secrets
If you complete all 129 goals, you will unlock the following:
Cool Specials
Kid Mode
Roller Skates
Flame
Always Special
Perfect Skitch
Perfect Manual
Moon Gravity

Perfect Balance
Enter "letitslide" on the cheats menu.

Moon Gravity Code
Select "Cheat Codes" at the options menu, then enter "getitup" . You can also get this code if you complete all 129 goals.

Unlock Everything
Enter havethemall in the Cheats Menu.

Man digs goat
In tampa go behind the strip club and you will see a man staring in a goats butt

Moon gravity
Getitup

Moon Gravity Wall Jump
When you have moon gravity on (getitup) to get an everlasting combo start a combo on the ground then continue it into a wall jump and keep wall jumping. You will notice that you keep getting higher and your points increase. Make sure if you wall jump on a building that you don't go too high on to roof or you'll end your combo. Keep doing tricks now and again though cuz the score stops increasing. make sure not to hit ground. I did this and got a combo score of 1038765450!

Perfect grind
Letitslide

INFINITE WALL JUMPS
All you have to do is go to the main menu go to options then go on cheat codes and enter GETITUP then go to the level manhatten pause the game go to options go to cheats and MOONGRAVITY press X so that OFF is ON then un pause the game then press L1 and R1 and jump and keep on pressing UP and X on a building and you're jumping UPWARDS how cool is that.

Man digs goat
In tampa go behind the strip club and you will see a man staring in a goats butt

T.H.U.G
If you beat the game on SICK mode you unlock T.H.U.G which is a monster thing that is in the beginning video.

Ney york secert tape
Go the billboard with a ladder tht you can see that has the tape on it

How to do a one hand stand
You have to push back on the analog stick and then at the same time triangle while you are up in the air

Easter egg
In Hawaii there is a weird looking tiki. When his eyes turn red jump into the mouth and you will end up in a location called Evil Tiki.When you go in you will have sudden death of lava There is no point in this easter egg exept it gives you a old skool icon.
See the video: Cheat Video

Unklocking secret levels.
While in New Jersey, go to the train station. Above the quarterpipes by the hospital,there is an item. So grind down one of the rails for speed and then ollie up to the white little ledge above the quarterpipe. Grab it and you will have the School 2 level from Tony Hawks Pro Skater 2.

Hawaii's secret tape
Go to the hawaii level, go down the road to the right, then turn left, go down the road until you find a tiki head and then do a kickflip into the mouth

Immortality
Go to the character appearance setup screen. his has to be your skater]Go to information
and make your name Pain. Time to test. Go to create- a- park. Put one Quarter pipe in. Then test play. Go to the Q-pipe and skate up it SLANTED. It will look like you'll smash your face in the ground... But you land safely! So go ahead- do multiple tricks! NOTE: you might get a sloppy minus deduction. And this cheat has it's weak spots. Sometimes, if you bump into a wall, you'll get hurt. SOMETIMES. And that lady in the suit at manhattan, she'll punch you if you try to knock her down. No matter what. So, who wants cheats?!

Moon gravity- getitup
Perfect rail- letitslide
Perfect manual- keepitsteady
Perfect skitch- rearrider

Well, Bye!

Hidden tape 1
Go 2 the bridge were its blocked off at in the new jersey level don't jump over were the cops r at jest stop your board runn down were it has a hill when you see a floating tape grab it and the message secert tape should be found

Jump out of a car!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!REALLY FOR REAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
OK you get in a car in hawaii then the girls by the pool are your target smack your car into them turn around keep going 4 bout 10 seconds and then hit the jump button the car will stop there and be parked P.S.! Next time you get in think bout these hints you can hit other vehicles and people! AND.....................If you Jump from vehicle to vehicle your able 2 switch vehicles vehicles and the 2nd time youdont have 2 hit the girls to jump.
And if you jump on the windshield of the car to control the other car you start with.

Moon gravity
Getitup

JUMP 5 FEET
GO TO option then tipe highjump

PS2 Cheats for Tony hawk's underground

Tony hawk's underground cheat codes

Tony hawk's underground cheats