Start a new game and type following at the entrance door:

120763-090665

Hold CTRL and klick OK, now hold CTRL and press 0(zero) and choose not to start a new game. Instead you open one of your saved games as you get access to these codes:

LOBBY

DRUM

HALLI

TAPESTRY

GARAGE

CHASM

DALI

ATTIC

CELLAR

VRROOM

JUNGLE

Type the codes while you are playing and then hit the ENTER key, when done you´ll come to the place in the game that you typed.