Press CTRL + SHIFT + S when you hear a sound, enter the desired cheat:
gold - Max gold
mana - Max mana
explore - Toggle Explore the whole map
fog - Disable fog
research - Research all spells
win - Win scenario
freemove - Toggle Free movement
towns - View all towns in the current map
lose - Lose scenario
spells - Toggle Free spells
instantprod - Toggle Instant Production
instantres - Toggle Instant Research
ai Toggle - AI on your own player
upgradehero - Upgrade hero
emergehero - Summon Hero Spell
cityspy - Toggle spying of enemy cities