Probably also forgetting about League of Legends. It's free, so no actual game sales are happening, but people spend a tremendous amount of money in-game.

The article also mentions that DLC and free-to-play games (along with in-game purchases, I'd assume) weren't counted in the Steam sales numbers, so the Steam marketshare shown could be a low estimate.

Walmart is still a gigantic part of some games PC sales. It's the reason why Valve is careful not to ask anything of the big publishers that would endanger their agreements with Walmart. That's why even though the cost to get a game through Steam is 10% of what it is to get it at Walmart, you still pay full price and often more than what you pay at retail. The big Steam discounts are only possible after the game has been removed from retail, since the retail agreements require not offering the game anywhere else for a lower price (though retail outlets are able to offer discounts from the MSRP which is why you might find a game that is $60 on Steam for $55 at Walmart). It's also why the stupid "preloading" system exists where you download a game you paid for, but aren't allowed to run it until retailers have a chance to put it on their shelf.

> Good luck even finding PC games in a box in a retail store...

Really? The most popular retail PC games are easy to find at a variety of stores in the south-eastern US. I've seen them at WalMart, GameStop, Best Buy, Fry's Electronics, and MicroCenter.