Now I understand why so many homeworks I had to do as a student involved right answers: specific numbers, computer programs that either ran or didn't run on test data, multiple choice. It's because it's much easier to grade; in some cases it can even be automated with those ScanTron things.
Even the essays I had to write were typically on a given subject, and everyone in the class was writing a different variation of the same essay. These are harder to grade since you actually have to read them, but it's still relatively easy because you know the kinds of things you're looking for.
Well, I made the mistake of starting my first assignments with "choose any game"... so everyone's assignment is going to have different content. I also didn't specify an exact format, so some people write paragraphs while others give bullet points (and both are equally valid). So for each student I first have to look at the game on Mobygames and Wikipedia and IGN/Gamespy/Gamespot to understand their game, then look through their description and see if it's reasonable. With 30 assignments total between my two classes, that's a bit of work.
Next time I give these classes it will be easier. I won't need to prepare each lecture in advance (I can re-use most of the content that I'm creating now) so I'll have extra time for grading. I'll also give an example of what I'm looking for so that students have a format they can follow.