During game-play press 'Enter' and enter the following codes then press enter again.
Allow buildings in the capital again: anotherbrickinthewall

Peace with all countries: givepeaceachance

War with all countries: badtothebone
Alliance with all countries: cometogether

All party members almost at next experience level: jump

All party members level up: stairwaytoheaven

Revive fallen units: lifeisacarnival

Know units within enemy cities and generals: allalongthewatchtower

AI does not notice you: invisibletouch

Advance to a day: letsdothetimewarpagain
Mana and gold set to 9999: moneyfornothing
Reset party movement points to full: borntorun

Heal party: help!

Win mission: wearethechampions
Lose mission: loser

Hide map: paintitblack

Reveal map: herecomesthesun