1. onlinecargames.com: "car games" has an exact monthly google search volume of 4,090,000
The relative value of the search volume gets a little choked out by competition -- more than 9 million exact match results for "car games;" nearly a billion broad match. The dev potential is pretty great, and I think anyone in the game niche would see it (look at some of the top SERPs, like cargames1.com, and you'll see that people are getting kw domains to differentiate themselves in the niche -- to what extent that pushes up the value of onlinecargames.com, I cannot say, but it must surely be a factor.)
I would think that given the potential to develop, you should not take less than $100 for the domain if you were to put it on the market. For barely more than that, you can drop in an arcade script and host it, get some ad revenue going, and have a site you can sell on Flippa or another venue for substantially more.
2. freegamesonline.net: search volume 301,000 (exact, google)
Limited dev potential = limited end user value. A domainer might give you money for it, since they are the most optimistic bunch around, but FreeGamesOnline.com has been around for many years, and any attempt to develop a competing (or even complementing) site, which would naturally involve overlapping keywords for SEO and PPC efforts, could trigger a "confusingly similar" bad faith argument in a WIPO proceeding, which would likely mean you lose the domain.
3. forgames.com: 14 years old
Nice brandable; I concur with Klem that it's a low xxx domain.
4. cooking-games.com
5. puzzle-games.com
Nothing. Develop them or let them drop.
Frank