Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Today on his blog, popular independent game developer "Notch" addressed a question he has gotten a number of times: Why is Minecraft not on Steam?
At PAX, I got asked why we’re not on Steam with Minecraft, and I had to answer the question straight out for the first time. So I’ll repeat what I said on here, because open-ness [sic] is awesome.
Steam is the best digital distribution platform I’ve ever seen. I’ve spent incredible amounts of money on it, and I own a crazy amount of games on it. It runs great, offers great services like that shift+tab stuff, and it remembers my credit card details so there’s no barrier for me when I want to buy a game. The only downside I can think of is that offline mode is a bit flimsy, and that the game list is sometimes full off DLC releases for stuff I don’t even own, and those are some tiny complaints!
Being on Steam limits a lot of what we’re allowed to do with the game, and how we’re allowed to talk to our users. We (probably?) wouldn’t be able to, say, sell capes or have a map market place on minecraft.net that works with steam customers in a way that keeps Valve happy. It would effectively split the Minecraftcommunity into two parts, where only some of the players can access all of the weird content we want to add to the game.
We are talking to Valve about this, but I definitely understand their reasons for wanting to control their platform. There’s a certain inherent incompatibility between what we want to do and what they want to do.
So there’s no big argument, we just don’t want to limit what we can do with Minecraft. Also, Steam is awesome. Much more awesome than certain other digital distribution platforms that we would NOT want to release Minecrafton.
The Minecraft creator and Valve policies seem to be at an impasse, with the game's appearance on Steam meaning that one side would have to give up something important. Gamers waiting for a Steam release to try Minecraft might not want to... mine elsewhere... aw dammit, I got nothing. Check other sources is what I was going for there. Get Minecraft somewhere else is what I was trying to say.