Tony Hawk's Underground Cheats

Cheat codes enter them

Start at the entrance of the stadium (where the parked trucks are located, and where you get into the contest. From there, look at the tape. You should see it above the glass dome behind the subway-like spline entrance. Go down left from here and wait for a vehicle to drive out of the tunnel. Skitch it towards where you started from. Make sure you are on the left side of the car. When you are about to pass the subway entrance spline, get of the vehicle and spline the entrance from the side. This will launch you across the dome into the secret tape.

At the main menu select options and then select cheat codes and:

1.Enter "letitslide" for perfect rail
2.Enter "keepitsteady" for perfect manuel
3.Enter "getitup" for moon gravity*
4.Enter "moveinfast" for increased speed

Enter holeshot at the cheat menu

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

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

This isn't much but it helps with beating Eric within the time.

ok- you have to get all the green fist icons while following Eric around
Jersey. The hint is that you DO NOT have to do everything he does,
meaning you don't have to grind the things he does to get the icons, and
to get the icons all you have to do is skate near them.

P.S the Fire That He Drops HURTS, so either go around it of jump over
it. (normal jump wont do it so bonless over them )