Press start and choose 'Quest Mode'. Then choose 'Use Password'. Choose the letters or numbers and press enter. 1=A 2=E 3=I 4=0 5=U in the game. It doesn't let you use vowels.
Password:
Result:
B1N1N1
level 1
1PPL2
level 2
GR1P2
level 3
4R1NG2
level 4
M2L4N
level 5
CH2RR6
level 6
P21CH
level 7
B2RR6
level 8
L2M4N
level 10
L3M1
level 11
P21R
level 12
M1NG4
level 13
P1P161
level 14
C4C4N5T
level 18
T4M1T0
level 23
See more: Castle Quest Video Game Console Cheats...