Various Codes
Hold down L + R + Y + Down for 3 seconds to enable cheats, then press:

Disable Fog of War:
R, L, R, R, L, L, Y, Y, L, R

Slow Down:
L, L, L, L, L,Y, Y, Y, Y, R

Speed Up:
R, R, R, R, R, L, Y, R, R, R

God Mode:
R, R, R, L, L, L, R, L, Y, R

Level Select:
Y, Y, Y, L, R, L, L, R, L, R, R, L, R, L, L, R, L, R, L, L, R, L, L, R, L, R, R, Y, Y, Y

Win level:
R, R, L, L, L, R, R, Y, Y, Y

+100 Gold:
L, R, R, R, R, L, Y, L, L, L

+100 Souls:
R, L, L, L, L, R, Y, R, R, R

+1000 Gold and Souls:
R, R, L, R, R, Y, Y, Y, L, L

Level 1: Easy Health
When controlling a Stone Ogre and your health is low without any Hellfire to eat, scoop up one of those annoying sheep. This is a good strategy for retreats, and the sheep will give more health than Hellfires.