If you're into alternative music, you probably already know that 1991 is generally considered to be "The Year Punk Broke," due in large part to a documentary of the same title that came out the following year. What that implies is that '91 was the year that punk rock not only changed internally (basically going from Sex Pistols/Ramones-style hard and fast to Nirvana-style hard and less fast, time has shown that "grunge" is a label that simply wouldn't stick, and with numerous good reasons), but also broke into the mainstream, and ran hair metal out of the proverbial town on the proverbial rail. 2008 seemed to me to be downloadable gaming's equivalent, which is not to say that games on PSN, XBLA or WiiWare bested the giant that is The November Rush (especially not WiiWare), but they made a big dent, and many downloadable titles are appearing on "Best of" lists for 2008.
The fact is that games like Braid, Castle Crashers, and, of course, Mega Man 9 showed that a game does not need to have a massive budget to turn a massive profit. All things are relative, of course, but if your metric is a cost to earnings ratio, games like Bionic Commando: ReArmed made way more money than most AAA retail titles. ReArmed sold over 130,000 downloads in its first week. Peanuts compared to Gears of War 2, to be sure, but compared to nearly any downloadable console game prior to 2008, that's selling like gangbusters. It's also more than No More Heroes sold in its first week, which, while a niche title, sold enough to secure a sequel.
There's also the matter of gameplay. Downloadable games have significantly less overhead cost (no printed manual, no plastic case, no shipping, etc.), and, therefore, the designers and publishers stand to lose a lot less if a game tanks, so they can take chances. They can make games with new ideas, or they can make games that are designed to make you believe they were actually made 20 years ago. The latter, of course, seemed to work out very well for Capcom.
In fact, downloadable titles in general seemed to work out very well for Capcom. Two of the games on my personal Best of 2008 list were downloadable titles from Capcom (Mega Man 9 & Bionic Commando: ReArmed). Capcom seems to be the first big developer/publisher to realize just how much money they can make, and great games they can release (not to mention nostalgia they can stripmine) using download services. This year, Capcom released more downloadable titles than any other 3rd party publisher (not even counting their real retro releases on the Wii's Virtual Console). In fact, Sony has given them their own storefront on the Playstation Network because of it.
2008 was a paradigm shift. I'm not saying that 2009 is going to see more downloadable game sales that retail sales. I'm not even saying that 2010 or 2012 will see that, but I think things are going to be a lot different in the next generation of consoles, and gaming historians will point to 2008 as the initial tipping point, but for now, I'm just glad that both retro games and retro styled games have a good, safe means of distribution, because, hey, I'll admit that side-scrolling action games are my favorite genre of all time.