I am a user of both Steam (http://store.steampowered.com) and Impulse (http://www.impulsedriven.com), so I thought I would compare and contrast them. It is nice that we have some competition and choice among digital game distribution for the PC, as opposed to the consoles, where the manufacturer has a lock on the services.
Steam, from tremendous game maker Valve, has got a tremendous selection of games, particularly very popular, mainstream titles. Impulse, from user interface wizards and game publisher Stardock, doesn’t have nearly as large a catalog, but does sell a number of big-name titles and, because it is the underdog, it tries a little harder. I have purchased a number of games from each and have had only good luck with both.
Steam has particularly annoying copy protection, which in normal mode launches Steam and signs you in over the network every time you want to run a Steam game. This is not a terrible burden, but it is a delay and could be problematic if your network connection is lousy. Apparently there is some sort of offline mode, but I haven’t tried it, so I can’t comment on it. Steam also installs your games inside its folder, which is bad if you’re looking to see if the game included a PDF manual or you are adding 3rd party mods (Oblivion, anyone?).
Impulse, on the other hand, verifies that you are legit when it installs the game, then never seems to bother you again. As far as I can tell, it doesn’t check in over the network or anything else. Impulse puts the game in the usual place (Program Files or wherever you install games). So for ease of use, Impulse is two steps ahead of Steam.
Both system give you several tremendous advantages over buying games on physical media. First, you can install the game easily if you get a new machine or on your laptop for travel and you don’t need the DVD in the drive (which is a practice that should be banned). I hear that some games have an installation limit, but it is normally pretty generous, like 5. Now that doesn’t mean you can (or should, at least) play the same game simultaneously on more than one computer, and I presume Steam would prevent that, but I imagine Impulse wouldn’t prevent it (though the game itself might). With both of these approaches, you don’t have to worry about losing or damaging your media, but you do need to remember your password and must worry about the company’s financial solvency. In addition, you don’t get a printed manual with the games, but that’s becoming the norm anyway, and much to our loss.
The biggest problem with both of these digital distribution systems is that they tend to charge full price for the games, while stores like Amazon and Walmart often discount games, even shortly after release. For a long time, you could be assured of paying MSRP at both Steam and Impulse, but that has become much better in the last year or two. Because of competition, both have sales every week, and sometimes, they are tremendous sales, like when I got Oblivion GOTY Deluxe for less than $8. The other great thing these companies do is put together game packs, like the whole id or THQ or Eid0s catalog, and sell it for a huge discount. Even if you only play a couple of the games, it is worth the price.
So both Steam and Impulse have pluses and minuses. I would say that if a game were the same price on both stores, I’d buy the Impulse one because of the constant checking in with Steam, but both are worthy sources of games. If you only have a Steam account, give Impulse a try, and vice versa.