Here are the level codes:
 
 JAGUAR,BANTHA,TOHOLD,COMBEL,SHIVA,PICOLO,ANTIC,
 KASYYK,FUGU,NOLAN,SARLAC,CAPSUL,ARTHUR,MAENOC,
 ZZZAP,SHIRYU,SULUST,MANIAC,RENDER,NEPTUN,NO WAY,
 BELUGA
 
 There's also a handy bug in it:
 Walk as close as possible to a wall, or a closed
 door you want to go through. Turn back, start
 running away and immediatly, turn back while 
 running, towards the wall.  If you release the
 [Shift] fast enough after starting to run, you
 go thru the wall.
 
 You will have to play around with that [Shift]
 key a bit to get the hang of it.
 
 The password PIXEL kills guards.