Come on, we know that's not true. I've been doing this a long time, I know how many times a consumer has to engage with a site to produce a sale. Nobody purchases a game on their first visit. That just doesn't happen.
I'm not having a go here, I'm trying to help. The keywords that are going to carry the most buying intent are keywords directly related to the game title. Lets say I wanted to buy "BioShock Infinite" for the PS3. I might well search for "Bioshock Infinite PS3". The page is dominated by Amazon and Play, plus you've got the game's official website, game.com, zavvi, all the supermarkets, the wiki page, then whoever's reviewed the game and their blogs and websites. You've got so much competition and you can't compete, it's as simple as that.