To use the cheat codes for this game, you have to edit the game file that you can find in the \gamedir\profiles folder. So, choose the autoexec.cfg file and make its copy, then open it in your text editor and add the following line at the bottom:
setvar dev_console_password = schwinge-des-todes
Now you can press ~ to bring up the console window and type the following codes in it:
add_skill [skill name]: adds skill points
add_exp [number]: adds indicated experience to selected hero
add_army town [town number] [0 or 1]: fills hero army with creatures from indicated town
add_all_spells: gives all spells to selected hero
set_hero_luck_morale [luck number] [morale number]: set luck and morale for selected hero
clear_money: all resources to 0
add_gold [number]: sets gold quantity
add_money [number]: adds indicated number of resources
show_player_money [player number]: shows indicated player's resources