The plural works better here because it's got a describing word in front of it. On it's own the singular would be preferable because it would make it more brandable.
You can back this up by putting in the word Game into dnsaleprice.com. The top 3 sales are plurals but have words before games but the top single word domains are singular.
I think there are exceptions to this rule. For example, Games.info would be worth more than Game.info for my money because information is a plural concept, the plural is more commonly used than the singular, and people would be expecting information on more than one game.
For keywords where the singular is used more frequently than the plural, I would stick with the singular. For example, I prefer Hotel.info to Hotels.info.
To gauge whether the singular or plural is used more regularly I put the word into a Google search. Game has 603m Google uniques versus 956m for Games but Hotel has 518m to 322m for Hotels.
This test doesn't always work because a word might have multiple meanings and one of those meanings might be driving the keyword value but another might be pushing up the Google uniques.
For example, Rates is one of my favourite keywords because it's flexible and commercial. I would rather have the plural in every extension but the Google uniques for Rate is higher than the plural because of the "How would you rate that?" additional meaning which isn't where the keyword value is coming from.
If I have a singular versus plural dilemma I often ask people who aren't into domaining what they think sounds better.