To activate cheat mode, press I while playing, then type "WINDY". To use a code, press any of the following while playing.

Code      Effect
ALT-F1    Access all spells
ALT-F2    More mana
ALT-F3    Destroy all players
ALT-F4    Destroy all castles
ALT-F5    Destroy all balloons
ALT-F6    Heal
ALT-F7    Kill all creatures
ALT-F8    More Spell Experience Points
ALT-F9    Free Spell Usage ON/OFF
ALT-F10   Invincibility ON/OFF
Shift-D   Complete current objective
Shift-C   Complete level