Since the gaming technology evolves so rapidly, videogame sequels generally surpass their predecessors.
However, most improvements are mainly superficial and/or accessory. Also, for most games there is rarely a reason for the continuation of a storyline (with Mass Effect being the only exception I can think of right now).
In terms of gameplay and interactive storytelling there seems to be very little to no innovation lately (regarding triple A titles). Just more of the same, bscly.
Now, you might argue that this has always been the case (in any major medium for that matter), also I admit that I may exaggerate a little, but don’t you think that in an industry that’s growing so rapidly with so many titles coming out every year, the next big thing to rock the gaming world is long overdue?
…sry, slightly off topic.