Use the following demo cheat codes! Note that this procedure involves editing a game file, so make its backup copy before cheating, guys!
To become invincible, go to the /deus ex invisible war demo/system/ folder and open the default file in your text editor. Find the following lines and replace hte numeric values by 0.0:
; Player Damage multiplier - damage player takes from AIs
Difficulty_Player_Damage_Easy__d=1.0
Difficulty_Player_Damage_Normal__d=1.0
Difficulty_Player_Damage_Hard__d=1.25
Difficulty_Player_Damage_Real__d=1.75
To unlock easy kills, open the same file and make the following changes:
; AI Damage multiplier - damage AIs take from player
Difficulty_AI_Damage_Easy__d=1.25 -> 4.25
Difficulty_AI_Damage_Normal__d=1.0 -> 4.0
Difficulty_AI_Damage_Hard__d=0.75 -> 4.75
Difficulty_AI_Damage_Real__d=1.5 -> 4.5