"Much like the instant depreciation when driving a car off the forecourt, as soon as you've opened a game, it's second hand and even if you'll never play it again, it's worth much less than when you bought it new, maybe only a couple of days before," says Simon Kilby, founder of new video game comparison and marketplace website Playr2.com.

It's with this in mind that Kilby set up Playr2, so that gamers can find the best deals on the games that they want to play. Of course, some gamers are happy to pay full price for a brand new game upon release, even if it only turns out to be a few hours long. Some, however, feel short-changed if they buy a game and have beaten it within a couple of days. This is particularly grating to people who don't play online much.

Taking this consideration into account, Kilby and Playr2 commissioned a study into which games players got through the quickest. 1,671 participants were asked to estimate how long it had taken them to beat various games without taking DLC or multiplayer into account. Results were then aggregated to discover an average amount of time per game. It may not be quite as scientific as actually measuring play time with a service such as Raptr, but it gives a good idea of player perception of game length.

Top of the pile was Call of Duty: Black Ops which was, on average, completed within 2 days. Then came Terminator Salvation (2.5 days), Resident Evil 5 (3.2 days), God of War 2 (3.3 days), Uncharted (3.8 days, later listed again as 6.6 days -- presumably one of the two is the sequel), Prince of Persia: Forgotten Sands (4.1 days), Assassin's Creed (5 days), Metal Gear Solid 3 (6.8 days) and Grand Theft Auto IV (8.2 days).

With those figures in mind, then, it may be worth shopping around for cheaper copies of the above games if you don't intend on playing multiplayer or DLC -- or indeed replaying them in the future.

This article originally appeared on GamePro.com as Study: Which Games are Completed Quickest?