Here is my theory on the great coin that is game innovation.
On one side, there is Innovation/Iteration. On the other is Gimmick/Cliche. Or maybe its 2 coins, Innovation/Gimmick, and Iteration/Cliche. Or maybe...whatever, you get the point.
All games have a little bit of all of the above. What games aspire to contain is innovation and iteration. Innovation is new, exciting ideas that havn't been tried before, and give the player a compelling new experience. Iteration is the use of tried and true approaches that give you a reason to expect that an idea will be enjoyable. Any good game will contain both. Lets take Portal, a universally loved game generally agreed upon to be a huge step forward in innovation. Well, there is still a healthy dose of the kind of iteration that makes people hate on sequels. For starters, there is Narbacular Drop. There was a continuation, and evolution, of pre-established ideas that had already been done elsewhere. Not only that, but it's Valve, you know they playtested the shit out of it before its release. In many ways a sequel is just a second draft of a game where the pool of playtesters includes everyone who bought and spoke out on the first game. What seperates the quality of Portal from a sequel that you hate lies in many things, but the virtue of being a sequel is not one of them. And of course, excellent sequels that excel because of the iteration of an idea still contain healthy doses of innovation. Half Life 2 continued the ideas of the original Half Life, and really most of the original pieces were still there. But it added new ideas, like the Gravity gun. The same pattern of mostly honeing a concept with a hint of new ideas is present in the countless excellent sequels that are better then the original, but it's a stickier area because popular sequels tend to be quite polarizing (Halo, Call of Duty, Starcraft, Bioshock...take whatever you like and look for the bits of innovation, and you will find your examples)
Where games fall short is where they become Cliche or Gimmicky. Cliche is where a game repeats what has been done before without adding anything compelling or new, while the gimmick adds in a new idea that just doesn't pass muster. What I need to point out here is that what separates a Gimmick from a true innovation is the spark of Innovations opposite, iteration. A gimmick falls short because it lacks the kind of testing and exploration that characterizes sequels, just as the iteration and polishing of an old idea without a bit of innovation turns into a cliche.
What to take from this? Well, we need to think about the shape of the games industry kind of like a recipe. When your making a cake, you can't say that eggs, milk, flour or sugar are bad. There all essential. In the same way, you need to have a mix of new IPs and ideas, and polished sequels. You need to explore old concepts more fully, and try new ideas. Simply decrying sequels as lazy will ruin one of video games biggest strengths. Yes, we need new IPs and need to explore new ideas, but we also need to remember that the best games out there are sequels.
