I just can't remember...
You know what gaming cliche gets used WAY too often? Amnesia. Just think about all the games you've played over the course of your life. How many of those games involved a character who had some form of amnesia? It's a friggin' lot, isn't it?! Now games aren't the only offenders when it comes to amnesia. Books, movies, and television (especially sitcoms) abuse this condition so much that you would think half the people in the world were amnesiacs. It's a plot element that can generate some kind of mystery and lead to a dramatic reveal, but it can often come off as a lazy cop out because the writer couldn't figure out any other way to make the story seem intriguing. Games can abuse it even more though, as it provides an excuse for a tutorial level. Many games want to let you live the fantasy of being the most badass fighter around, but also want to integrate a tutorial into the gameplay. So how do they do this without making the character look like a clueless wuss? Well they just give him/her amnesia! They don't remember who they are, so they have to learn how to fight all over again.
Now I don't think amnesia is always lazy or is always a negative thing. Alan Wake recently used it in a very effective way, and some of my favorite games of all time relied on it in some measure. But I'm going to list out the games that I've played that have an amnesiac in a major role to show a picture of just how many games use this concept. And again, these are just the games that I have personally played. I know there are far more out there. Maybe game writers should take a little more time to think up some different ideas before they choose to rely on the amnesia crutch again.