Gameplay can't get better: Half-Life 2

I had not played Half-Life 2 when I thought Call of Duty had the best gameplay. Having said that, I am not taking anything away from Call of Duty; not even comparing as both are of different genres. Just that I liked this game almost as much as Call of Duty. Half-life 2 has very well designed graphics and awesome gameplay. I must say that one has to be too intelligent to finish the game without any help. There were many occasions where I needed help, but somehow got myself out of the conundrum. For instance there is a place where I have to open a big door in the middle of the road so that I can take my bike through. There was a room that had one battery on the table - there were 2 more slots. I confirmed that this was connected to the door and figured out that I must find 2 more batteries and lay it on the empty slots to open the door. One battery was found outside, but nowhere could I find another one. There was a damaged car in a distance and guess what - found the battery i...