Some of the games are only "games" in a loose sense of the word, and seem to be more like a Choose-Your-Own-Adventure series of webpages (they call themselves "interactive dialogues"), with a lot of text to read and a few choices to make at the end of each section. Others, however, are simple but genuine games - perhaps not as fun & addictive as web-based games such as Bejeweled or Castle Attack 2, but more educational. If you want a quick brush-up on economics, I'd definitely suggest these games over a textbook (at least for the principles they cover).
I think this is a good first-generation effort towards trying to show how & why economic principles work rather than merely explain them. You don't need to just "have faith" in the market or your econ prof once you've experienced how it works for yourself. Sure, you still have to believe that the game designers aren't trying to pull one over on you, but I think with fairly simple, upfront games like this, that's not really a big concern. Once we start producting free market versions of games like Civilizations or The Sims or Everquest, there's a lot more going on behind the scenes that will trigger suspicion of intervention by deus ex mercatus, as it were.
Further, there's the problem of what to give a player to do in a "free market" or "libertarian" game. You can certainly put them in the role of a businessman, but then it simply becomes a business simulation like Capitalism II or Railroad Tycoon (and the many "Tycoon" spin-offs), which might convey a few market principles but doesn't help one get the big picture of how regulation and the market interact. For the sort of "big picture" societal-level game like Civilizations or Sim City, it's hard to design a game that isn't essentially a command-and-control society with the player as despot - precisely the message we're trying to avoid. (Yes, I'm aware that there are "democracy" and "republic" modes in Civilizations, but they don't really function realistically - instead, they just impose some limits on your control in exchange for increased wealth or other benefits - but at the end of the day you still get to control just about everything going on in your nation.) Maybe I overestimate the influence of games, but I actually think that an entire generation of kids that grew up playing SimCity is much more likely to accept land use planning such as zoning because they're familiar with how it works in the game, and because SimCity doesn't show any alternatives to zoning - there is no Houston-style spontaneous growth in the game.
One potential option for avoiding this pitfall is following the example of games in which the player himself is fairly passive but attempts to create the correct incentives for automated characters in the games to do things. Games with strong elements of this type of gameplay include: Lemmings, in which the player tries to herd a suicidal flock of lemmings, Dungeon Keeper 2, in which a player attempts to build a dungeon that will attract just the right sort of monstrous denizens to attack the "heros", Startopia, in which the player attempts to design & run a space station/resort that caters to a variety of alien clientele with very specific (& sometimes conflicting) living needs, Majesty, in which the player attempts to run a kingdom by creating incentives (in the form of rewards, etc.) for heros to kill monsters, rescue damsels in distress, etc. Even perhaps Black & White falls in this genre, as you play as the god of a small tribe and control your avatar - both the avatar and your followers grow, change & act in response to your treatment. A socieal-level game with similar game design, in which a player discovers the right economic incentives to make a society run smoothly and efficiently without sacrificing valuable things such as happiness and individual rights, may help communicate the message of liberty to a new generation. Or, it could be ignored in favor of DOOM XVI; it's just too hard to predict what will appeal to the gamers of the future.
