I generally avoid buying games for the same reason. Few really advertise their core mechanics, and even the ones that do, I have no way to trust them on how well executed they are. For cheap games, I am willing to take the risk because even if the game is 'bad' I will still generally come out with a decent $/hr ratio. But the only times I get 'expansive' games are if I have seen a lot of people play it to the point where I have a good sense of how it works. Most games do not have a large enough network effect to get to that point.