I think the video game left 4 dead is awesome because of the element of choice involved.
and I don't mean choice in the sandbox game kind of way. In GTAIV, sure, you could choose which mission to do when or even not to do any missions at all. But if you don't do any missions you don't even get the sense of accomplishment you can in a real sandbox by building, say, a sandcastle. and when you do choose a mission, there's really only one way to do it. I ended up abandoning GTAIV because I got too frustrated trying to chase someone in a car and shoot at them at the same time. I always ended up with four flat tires and a decidedly not-dead rival gang member.
Left 4 dead has a different kind of choice involved where you can choose the process instead of the product. Everyone is trying to kill zombies and get rescued, and you can't really choose where you get rescued or anything but you have MYRIAD ways to kill zombies. propane tank? pipe bomb? sit on a park bench and snipe their heads off? Check, check, and CHECK. add to that the possibility of four human players working together and you have so many more creative ways to fend off zombies, from simply healing and protecting each other to laying traps.
strangely enough, this is what I try to do in the classroom when I can. I have set objectives I need the students to achieve, but as often as I can I try to give them choice in the process they use to get there.