The day before Thanksgiving, Amazon was offering a discounted price of $49.96 on a popular Xbox game, the same price as Walmart and 3 cents lower than Target.

Then the holiday pricing shuffle began.

Amazon dropped its price on the game, Dance Central 3, to $24.99 on Thanksgiving Day, matching Best Buy’s “doorbuster” special, and went to $15 once Walmart stores offered the game at that lower price. Amazon then brought the price up, down, down again, up and up again — in all, seven price changes in seven days.

The unluckiest buyer paid more than triple the price that the luckiest buyer paid.

Retail price wars online have entered a new era of speed and precision, creating a confusing landscape for shoppers in which prices leap and plummet on short notice. In the old days, merchants sent employees into competitors’ stores to check on pricing, and days later “sale” signs reflected new markdowns. Now, sophisticated computer programs accomplish the same goal online within hours, and even minutes.

The battle was fierce over the holiday weekend. At the request of The New York Times, the pricing firm Dynamite Data tracked prices at three major online retailers — Walmart.com, Amazon.com and Target.com — starting the week before Thanksgiving and going through Tuesday, after most heavy promotions ended.