Press Ctrl + Shift + C during the game and enter one of the following codes:
1000 gold: gold
1000 mana: mana
All spells researched: research
Current level completed: win
Current level lost: lose
Toggle exploration of entire map: explore
Toggle fog: fog
Toggle free movement: freemove
Toggle free spells: spells
Toggle instant production: instantprod
Toggle instant research: instantres
Toggle your player's AI: ai
Toggle spying of enemy cities: cityspy
Upgrade hero: upgradehero
View all towns in current map: towns