Use these passwords to unlock easy difficulty levels:
ZZB: Episode 1
ZVC: Episode 2 mission 1
QZB: Episode 2 mission 2
QVC: Episode 3 mission 1
!0G: Episode 3 mission 2
!XH: Episode 4 mission 1
R0G: Episode 4 mission 2
RXH: Episode 4 mission 3
Z2B: Episode 5 mission 1
V6C: Episode 5 mission 2
Q2B: Episode 5 mission 3
L6C: Episode 6 mission 1
!4G: Episode 6 mission 2
W8H: Episode 6 mission 3
R4G: Episode 7 mission 1
M8H: Episode 7 mission 2
0GD: Episode 7 mission 3
0BF: Episode 8 mission 1
SGD: Episode 8 mission 2
SBF: Episode 8 mission 3