Press Delete in 3D mode to open the message console and enter one of the following codes there:
Enable AI cheats: sesquipidilian
Set all buildings on fire: dresden
Disable blood: haemorrhage
Kill all opponents: bannockburn
Kill own troops: the five hundred
Kill camera: killcam
All troops harder to defeat: steve reeves
All troops retreat: bucks fizz
All walls breached: bastille day