I did not mind this linearity in Half-Life, because the story was engaging. You wanted to know what happened next. And I found the enemies did had some advanced

I did not mind this linearity in Half-Life, because the story was engaging. You wanted to know what happened next. And I found the enemies did had some advanced "AI" for that time; like the first time the commandos came was a big moment. They were nothing like the enemies you had seen in other games.