For many years gamers have moaned and groaned when a game was "too short." Throughout the evolution of the video gaming medium, there has always been a stigma attached to shorter games; that these games were rushed or that they aren't as good. Similar to the movie industry in its beginning, the expectation is now that every film will be an epic. While an epic might please some, video games now appeal to a wider audience. An audience that might not have time to play through the newest Final Fantasy game, but instead wants a quick fix or weekend-long experience.
Several reviewers gave Call of Duty 4 demerits for having a story that was "too short," even sites that are known for their reviews like Gamespot and IGN took off points for the game's length. While the game received universal praise for the great gameplay and story, some reviewers said that the singleplayer experience just wasn't long enough. Never mind the fact that Call of Duty 4 had excellent multiplayer that would last a gamer for months, the singleplayer took less than ten hours to beat.
When I was younger, I used to look at a game as a value proposition. If I pay $50 for a game, how long will I play it? Because if I play it for 50 hours, I'll be paying $1 for each hour of the experience. Looking back, I realize that that attitude was childish, the value of a game, or any piece of media for that matter, is about the experience not the amount of time it lasts.
Now that I am older and don't have as much time to play games, I no longer look at buying games by calculating dollars/hour, instead I look at how good a game is and how much it costs. Games like Call of Duty 4 are awesome to me because I can play the whole thing through in a weekend. There's a lot more content to explore in the game past the additional run through, so it's not like I'm done with the game in a weekend, but I could call it quits after that. I have gotten the basic experience and story out of the game, without investing a whole month into it.
Movies don't last for twenty hours for a good reason. The story just won't stay fresh that long. As video game stories get better, developers are going to find that it's hard to make a good story stretch over an epic length of time. Games like Call of Duty 4 keep the story moving better than games that take weeks to play because the whole story becomes important instead of a few simple checkpoints in the story. For example, the entire story of Legend of Zelda: Ocarina of Time could be summed up by (Spoiler):
Link is told to go to the Deku tree. He fights monsters inside the tree and the tree gives him a stone, but then dies. He is told to find other stones, which he does, but first he meets a princess who tells him that an evil man is manipulating the king. Link takes all three of the stones to the Temple of Time, where he is sealed for seven years. When he emerges from the temple the world is horrible. He then frees the six sages, who are in different dungeons of Hyrule. Then he fights Ganondorf, who turns into Ganon. He kills him with the Master Sword and goes back in time.
That game took quite a bit of time to beat, but in order to understand the story, you need only read a short paragraph. None of the temples mattered at all to the story. I summarized the entire second half of the game in a few sentences. This isn't to say that Ocarina of Time wasn't a blast to play, it's just that the story wasn't concise and the action didn't progress because of the story.
Call of Duty 4 on the other hand would need about the same amount of space to describe with the same conciseness, yet the game was half as long. The action in the game progressed the story making for a deeper and more meaningful experience. With the exception of a couple out of place levels (like the Spectre Gunship level), the game felt like an action movie. The story wasn't an excuse to have the gameplay, the gameplay was part of the story.
For people who want a more complete experience and don't have time for an epic, short games make a lot of sense. Short singleplayer isn't necessarily a cause for demerits or malevolence, but often necessary for a well paced game. It's not that short games are more fun and shortness doesn't make a game's story better, but it's easier to write an exciting story that will last for five hours than fifty hours. The future of games is to play the game for the story, not to listen to the story to get to the gameplay.