There was lots of speculation surrounding how exactly the system would work, including from myself. As it turns out, Greenlight is a far more simple solution than anyone could have expected.
The Greenlight front page displays submitted games in a tiled format, with users able to scroll through page after page of indie games, initially judging them based on name and square image alone. There have been over 500 entries added to the list already, so it can take a while to skim through the entire library.
Much of the speculation regarding the system focused on discoverability -- how would Valve answer the age-old question of how to best display the games in such a way that every title has a fair chance of being spotted, while the best games rise to the top?
ConcealabilityThe answer, it would appear, is to barely even address the problem at all. Greenlight features absolutely no ranking methods -- you can't list games by popularity, ratings or anything else. In fact, the only way you can cut the selection down is by genre, platform or number of players.
What this means is that games can only become popular through three different avenues. First, a game can be rated up via a user simply clicking through the many pages, spotting a game they like, and upvoting it on a whim. Then there are also "Collections" that have been put together under their own tab, where users can band together all the games they believe are worthy of a rating. Other Steam-goers can visit Collections and decide whether it's worth taking the advice of the Collection owner. Well curated collections such as my own IndieGames.com top picks collection are a great solution.
Finally, and most prominently, games can be voted up simply by already having a notable fanbase. Games like Project Zomboid and Octodad: Dadliest Catch are already well on their way to rating stardom, thanks to their prior press and the fanbase built around them. This is going to be the main method by which a game is chosen by Valve: rather than building up your fanbase via Greenlight, you're going to need to do that popularity building outside of Steam before going for glory.
This may seem like a problem with the service, as newer games that deserve to be on Steam most likely won't be able to quickly build up the votes needed simply through Greenlight. Yet this is most likely exactly what Valve was aiming for. At the end of the day, even if you have the most incredible game around, if you don't already have a fanbase of people who are going to buy it, why would Valve want to stock it? This isn't charity - it's a business.
The most interesting thing about Greenlight is the feeling you get that this is probably what Valve has to go through every single day. Hundreds and hundreds of submissions, with only a small percentage actually worth adding to the Steam store -- it's as if Valve has set Greenlight up for the sole purpose of showing us exactly what its submissions team has to wade through, and why we should really cut them some slack. By letting us see under the bonnet, we're now a little wiser as to the awful task that Valve has to go through.
Rather them than us, from what we've encountered. In just the first 24 hours of Greenlight going live, we've seen all sorts of ridiculous, terrible submissions piled onto the Greenlight pages -- and that's without even mentioning the plagiarized titles. At last count we've seen Minecraft included over half a dozen times from different users, while both Team Fortress 3 and Half Life 3 have also made appearances. Some are obvious forgeries, but other times it's difficult to work out whether the submitter is actually the game's author or not.
Indie games are lameThe entire system has also brought to light an issue that we were all very well aware of, yet perhaps not to this scale -- the average Steam community user is not the sharpest tool in the shed. Head to the "Discussions" tab in Greenlight, and you're met with a forum full of giddy users harping on about how their favorite AAA title isn't on Steam, and why are there all these silly indie games taking up the space that "real" games could be filling?
One random forum post as an example: "This system seems kinda lame. So it's just an indie game thing, great. I'm going to have to look at EVERY single game and rate them when none of them are really important at all. Change the caption to something other than 'Games you want' because it's frankly misleading, and looks like a complete waste of time. Maybe if I rated so many games I'd get SOMETHING other than just lost time..."
This is followed up by dozens of comments from users agreeing that indie games are awful, and that the entire system is terrible for trying to promote them. How, then, are developers without an existing fanbase meant to battle against this tide?
There are issues with the system itself too. Game creators are able to delete comments left under their game on its Greenlight page, meaning they can simply remove all the negative comments and leave the positive ones. This was clearly not the intention that Valve meant it for, but it is an area which needs clearing up pronto.
Submitted projects can also only have one "creator" account, meaning that it is tricky for a team of more than one person to alter a profile and talk properly to commenters. It's all small bits and pieces like this that aren't a huge deal separately, but when all added together, make the system less useful than it needs to be.
Of course, it's still early days. Greenlight only launched yesterday, and overall has been a positive move. Valve is clearly keen to keep it as professional as possible too, removing plagiarized content as quickly as it appears. How Valve decides to tackle discoverability is going to be where the system succeeds or fails. As of now, the only winners are going to be those developers who already have a fanbase, and those devs who are just starting out needn't bother applying.