I don't disagree that if something like that were to happen, there would still be pressure on both users and developers to continue using Steam. But at the same time I don't think they would have the same dominant, unassailable position that they do now.
To be honest, I'm not sure what your arguing here. That Steam have established some kind of unbeatable monopoly?
Well, the quote that started this tangent asserted that the functions that Steam provides the end user with were unrelated to the reasons that companies elect to go Steam exclusive. That was pretty much the only point I was making, though; that the tools Steam provides developers with, combined with the limited marketshare of Steam's competitors, made it an attractive option.
I could argue that Steam has established an unbreakable monopoly position if you'd like, though? I wasn't arguing that, but given the way the conversation has developed, it would be a natural direction to go in.
I would agree with the claim that the number of people who "feel forced" is greater than one. But both of us lack any evidence as to what the actual number is, and given that by and large the Steam userbase seems anywhere from content to happy with it's service, I think it's safe to assume that the people who "feel forced" are small minority. But they exist, I grant that.
I shall in return grant that it is, in all probability, a small minority

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When you have the time, you really should read the article/check out the site. It has some pretty neat materials.
The article's main point is a bit involved and technical to reproduce here in shorterned form, but I'll try. Cutting out all the setup and such, the most relevent part reads:
I would call doing something which you yourself say "wouldn't work" to be a losing strategy, and I can't agree with calling that "rational".
Well, I was simply attempting to differentiate methods with a low probability of success from those with no probability of success in a concise manner. If you'd prefer to use a different word for it, that's perfectly fine.
I'm not sure which game "that pinball game" is. But Greenlight is relatively new, not even a year old. I think it's fair to say that Greenlight came about as a result of whatever whine Valve receives daily about all sorts of different games.
The voting process is just whoever is interested enough in the project to make their voice heard, and I've seen many Kickstarter projects give links to their project's Greenlight page. It isn't just whoever happens to stumble into the voting booth. I would argue that the bias doesn't so much favor games with a simple concept as it does favor developers who are good at marketing and explaining their product. This may still be unfair, but it's an unfortunate fact of life in many things outside game design, like landing a job interview. I don't like it either, but success requires marketing yourself.
I'm afraid I can't recall the name of the pinball game (totally not my area of interest), but I can't imagine there are many on there, given how much of a hassle it was to get this one on there. But I agree that Greenlight was likely instituted both to resolve situations like this, and to get new games approved in a timely manner as, if I recall correctly, their previous approval process for people they hadn't dealt with before was basically "have a staff member see if anyone sent us anything interesting, when we have time". This was particularly problematic given their (lack of a) corporate structure, as they couldn't just hire a bunch of interns to filter through things like a more traditional distributor could, making a bit of a bottleneck.
Anyways, background aside, what I'm saying is that in more diverse market, it wouldn't matter if Quirky Game #5 could catch the community's eye and be greenlit; in a market of, say, ten distributors of equal size, it wouldn't matter if a few of them overlooked the game - those that did would see people buy the game, and based on their results (or lack thereof), they'd have an actual record with which to seek admission to other marketplaces. Even if they were a total flop, the ten people who did enjoy it could still buy it and tell others where they could get it. With only a single market like this, however, it's functionally life or death for the participants - if they can't get on, that's the end of their career... And if you were one of the minority who thought a game sounded interesting to you, but it couldn't get approved, well... Tough luck. Guess you can never buy it.
To expound on my earlier statements regarding Greenlight, however, I should mention that the self-selecting nature of the voters is part of what makes it problematic to me; people involved in the Greenlight process are basically either those there for a single campaign (among them the kickstarter campaigns you mentioned), or those who have the time and interest to wade through a thousand randomized applications every few months. The first category of voters reward the best marketer rather than the best concept, a trend I consider problematic in the AAA market and don't wish to see spread to smaller ones, while the second category tends to have strong opinions that diverge from the market as a whole. And, well, let's be honest here. After you see your hundredth sprite-based platformer, you tend to stop caring about what it does differently, and start saying "Eh, we have enough of those, pass".
But to reiterate: Greenlight is an interesting approval process that does have many benefits. I just don't want it (or Steam's old approval process) to be the sole means by which games can be sold.
I wouldn't give up hope on your hopes of the Princess Maker series being Greenlit. A pretty wide variety of different games have been Greenlit so far, including games like "The Stanley Parable" that seems to defy explanation (Many people dispute it being labeled as a "game" at all). The only unifying factor is that every game that has been Greenlit has had a lot of passionate people who want the game to be Greenlit. As far as I can tell, that's the only barrier to entry.
Oh, no, Princess Maker is definitely never going to be greenlit; the only one of them translated into English was Princess Maker 2, released way back when computers were making the transition from DOS to Windows. The company handling the translation went into bankruptcy, however, and the rights to the English version ended up in a nasty snarl between three different companies; a beta copy of the translation has made the rounds of the internet since, and is the only exposure most fans have had to the series.
The series pretty much ended with Princess Maker 5, back in... Gosh, 2006, was it? 2004? Something in that range. Whatever the specific date, they never announced another sequel, and the head developer of the game resigned from Gainax after some loud dispute with 2chan over unrelated matters. I can't imagine they have any interest in releasing such an old series on Steam, but even if they were, I don't believe Gainax would need to go through the Greenlight process.
I was just using it as an example of a series that I adore that would unlikely be appreciated in substantial enough numbers to pass the approval system.
On paper, mechanically? Sure. With the difference that there's no application process, so literally anybody can "compete" and attract a fanbase.
In practice, this means it's quite different in that Greenlight is dominated by indie titles. It's more like American Idol if American Idol only had the Susan Boyles of the world, and the community gets to pick which they like best.
Unrelatedly, and I'm not certain what I'm about to say is actually true, I hear that many of the people who placed second or third in American Idol went on to be more commercially successful than the actual winners did.
This doesn't really have any (intentional) relation to the comparison, though. I just thought it an interesting bit of trivia.