I can answer this one!
Toys R Us has been bleeding video game market share for years, and the resurgance of Nintendo gives them a chance to put themselves back on the map. By offering great deals on Wii/DS games at such a critical time of year, they're trying to get people to associate great Wii/DS prices with Toys R Us.
In other words, they're hoping to increase their gaming market share long term.
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