The problem with thinking about this now is that it is far too easy to apply hindsight. We know how great it was then but now we can make it even better. But if the first ever Halo game is just due to be released this November, it would no doubt be graphically astonishing, but would it give quite the same impact as an Xbox ONE launch title amongst all of the other stuff as it did as an Xbox launch title? The first game defined the genre, so would the genre be different nowadays if Halo hadn't come along when it did? We cannot really say. What we can say for sure is that games will continue to get better and better, as is the basic principal behind gaming itself.
A benzene ring changes everything.