Will Call of Duty: Modern Warfare 3 be the best-selling video game ever?Pre-order levels at Game and Gamestation point to yes."Call of Duty: Modern Warfare 3 is the most popular game for pre-orders that Game and Gamestation have ever seen," Game spokesperson Anne-Marie Mason told Eurogamer."Beating records set by last year's number one game, Call of Duty: Black Ops, Call of Duty: Modern Warfare 3 is now Game Group's largest pre-order title in the company's history."In the UK, Call of Duty: Black Ops became the fastest ever selling video game by shifting 1.4 million copies in one day. Black Ops went on to overtake Modern Warfare 2 as the UK's best ever selling video game, with 3,722,411 sales.In March this year, number-cruncher NPD said Call of Duty: Black Ops had become best ever selling video game in the US.But HMV revealed to Eurogamer less convincing evidence that Modern Warfare 3 will rewrite the record books."We've seen pretty decent pre-order levels," said an HMV spokesperson, "but we feel most of the interest will be driven by over the counter purchasing, particularly now that we're into the early stages of Christmas shopping."Amazon pointed Eurogamer towards the pre-order and bestseller charts, which were both dominated by Modern Warfare 3. But when contacted at the end of last week, Modern Warfare 3 wasn't the shop's most pre-ordered game ever. We were told those numbers would increase as the 8th November release date for MW3 approached. And how they stand now, we haven't been able to find out.GameStop UK couldn't comment on Modern Warfare 3 pre-order levels.Since record breaker Call of Duty: World at War, each subsequent Call of Duty game - Modern Warfare 2, Black Ops - has set a new worldwide sales record. And with a larger console installed base to sell to each year, it's tempting to believe Modern Warfare 3 will continue that trend.There is, however, competition this year, from EA and Battlefield 3. But what effect this will have, if any, on Call of Duty-mania we're yet to see. Expect Modern Warfare 3 sales figures this week from Activision, if they're extraordinary enough.