AI "helpers" are very helpful on hard levels WHEN THEY WORK, mainly those who have unlimited health, the only actual helpful AI i can recall are the other soldiers with you in Call of Duty Modern Warefare, on the snowy levels and other places that i can't see what is in front of me so i just follow them and hide when the enemy pops up, and my favourite AI is from Time Splitters future perfect, they were invincable, they could fight, there were no items for them to use they would only attack if they were attacked or if they enemy noticed you, no running into the enemy on stealth missions, and the robot made for good cover in a firefight. Other than these AI though most of them are terrible walking into gunfire and losing the game for you, although i didn't find the AI in GTA4 as bad as some people have said.