Sometimes it isn't just the game you're playing, it's all the surrounding factors that determine how and why you're playing the game at that exact moment. The idea that external factors might affect enjoyment levels isn't something people often concede in game criticism, nor in pub arguments, because if you admit it that judging one game against another is anything other than a scientific process, the whole house of cards falls down. Personally, every time I think about Half-Life, the greatest game I have ever and will ever play, I see that house of cards levelled in front of me.