Tony hawk Underground

Perfect rail balance
Select "Cheat Codes" at the options menu, then enter "letitslide" as a code. Alternately, get all 129 goals.
Perfect manual balance Select "Cheat Codes" at the options menu, then enter "keepitsteady" as a code. Alternately, get all 129 goals.
Perfect skitches Select "Cheat Codes" at the options menu, then enter "rearrider" as a code. Alternately, get all 129 goals.
Play as T.H.U.D. Select "Cheat Codes" at the options menu, then enter "NOOO!!" as a code to unlock T.H.U.D. Alternately, successfully complete story mode on the sick difficulty setting. Note: In the Neversoft FMV sequence at the start of the game, the boy that gets eaten is Eric. The thing that pops out to eat him is T.H.U.D.
Moon Gravity Select "Cheat Codes" at the options menu, then enter "getitup" as a code. Alternately, get all 129 goals. -From: goldenatc@hotmail.com
All FMV sequences Select "Cheat Codes" at the options menu, then enter "digivid" as a code to unlock all FMV sequences.
Pre-made skaters Go to create a skater and change the name to one of the following entries. The character will change into the corresponding skater:

1337 (Rulon Raymond)
Akira2s (C Surla)
Alan Flores buffoon (Pete Day)
Alex Garcia
Andy Marchel
arrr (Captain Cody)
Bailey
Big Tex (green skinned cowboy with a cowboy hat, cowboy boots, Hawaiian shirt, shoots, and a tribal tattoo)
Chauwa Steel
Chris Rausch
ChrisP (Chris Peacock)
CodePirate
crom (Eric Grosser)
Daddy Mac (Dana MacKenzie)
Dan Nelson
Dave Stohl
DDT (Darren Thorne)
deadendroad (Ralph D'Amato)
fatass (Brad Bulkley)
FROGHAM (Kendall)
GEIGER (Jake Geiger)
Glycerin
GMIAB
Greenie
grjost
Guilt Ladle (Kevin Mulhall)
Hammer (Ted Barber)
Henry Ji
Jason Uyeda
Jeremy Andersen
Joel Jewett
Johnny Ow (Chum)
leedsleedsleeds (Wardy)
MARCOS XK8R
Mike Ward
moreuberthaned (Mikey Ortai)
M'YAK (Rock)
Noly (Nolan Nelson)
NSJEFF (Jeff Morgan)
POOPER (Paul Robinson)
sik®
Skillzombie
Stacey D
Steal2Liv
tao zheng
The Kraken
The Swink
THEDOC (Adam Lippmann)
Todd Wahoske
TOPBLOKE (Dave Cowling)
TSUEnami! (Todd Sue)
woodchuck (Michelle Deyo)
Y2KJ
Yawgurt (Gary Jesdanun)
ZiG (Zac Drake)

Cool Specials Get all 129 goals.
Kid Mode Get all 129 goals.
Rollerskates Get all 129 goals.
Flame Get all 129 goals.
Always Special Get all 129 goals.
Hangar level In the Moscow level, find the place where there are a lot of tanks and a building that reads "AEHNH". Stand in front of the building to the left. Line your self with the brown ledge. Climb up it. Stand on the brown ledge that you are about to grind on. If you are in the correct location, to your left should be a tree and straight ahead should be a big red building palace-looking thing. Grind that ledge and jump toward the previous viewed window. You should go down a ramp. Where the ramp is located, is a ramp that goes up on the right, revealing the "Tony Hawk 2" icon as you went down the ramp to unlock the Hangar level from Tony Hawk's Pro Skater 2.
Hotter Than Hell level Successfully complete story mode to unlock the Hotter Than Hell level.
Venice Beach level From the large hotel you start at in the Hawaii level, follow the main road all the way around in either direction. When you find the strip of buildings that are opposite on the map from the hotel, you will find a large tiki head. Alternately, go out the front doors of the hotel and through the plaza all the way out the other side. Jump inside the tiki head's mouth to find a secret area. Skate down the tunnel until the end and boneless into the air to grab the "Tony Hawk 2" icon to unlock the Venice Beach level from Tony Hawk's Pro Skater 2. Note: Think of the map as a square. If the beach is at the bottom, the tiki head is on the top side of the map. It is much easier to get inside the tiki head's mouth if you dismount your board first.
School 2 level In the New Jersey level, cross the bridge, then get on top of the large building immediately afterwards. Shimmy across the tall gate and pull yourself onto a ledge. There will be a "Tony Hawk 2" icon on the ledge alongside a tall building that will unlock the School 2 level from Tony Hawk's Pro Skater 2.
Play as Gene Simmons Successfully complete story mode on the normal difficulty setting to unlock Gene Simmons.
Play as Iron Man Successfully complete story mode on the beginner difficulty setting to unlock Iron Man.
Play as Pedestrians Find all gaps in the game to unlock the Pedestrians.
Create-A-Deck mode Successfully complete "Slamma Jamma" in story mode to unlock Create-A-Deck mode.